As filed with the Securities and Exchange Commission on August 3, 2018

Registration No. 333-            

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

COLUMBIA BANKING SYSTEM, INC.

(Exact name of registrant as specified in its charter)

1301 A Street

Tacoma, Washington 98402

(253) 305-1900

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

HADLEY S. ROBBINS

President and Chief Executive Officer

1301 A Street

Tacoma, Washington 98402

(253) 305-1900

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies of Communications to:

Patrick S. Brown, Esq.

Sullivan & Cromwell LLP

1888 Century Park East, Suite 2100

Los Angeles, CA 90067

(310) 712-6600

Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this registration statement.

If the only securities being registered on this form are being offered pursuant to dividend or interest reinvestment plans, check the following box.  ☐

If any of the securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or reinvestment plans, check the following box.  ☒

If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box.  ☒

If this form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) of the Securities Act, check the following box.  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐

CALCULATION OF REGISTRATION FEE

PROSPECTUS

COLUMBIA BANKING SYSTEM, INC.

Common Stock

Preferred Stock

Depositary Shares

Debt Securities

Purchase Contracts

Units

Warrants

Columbia Banking System, Inc. from time to time may offer to sell the securities listed above. The debt securities, preferred stock, purchase contracts and warrants may be convertible into or exercisable or exchangeable for common or preferred stock or other securities of Columbia Banking System, Inc. or debt or equity securities of one or more other entities.

Our common stock is listed on the NASDAQ Global Select Market and trades under the ticker symbol “COLB.”

Columbia Banking System, Inc. may sell these securities on a continuous or delayed basis directly to purchasers, to or through one or more agents, dealers, and/or underwriters as designated from time to time, or through a combination of these methods. For additional information on the method of sale, you should refer to the section of this prospectus entitled “Plan of Distribution.”

This prospectus describes some of the general terms that may apply to these securities and the general manner in which they may be offered. The specific terms of any securities to be offered, and the specific manner in which they may be offered, will be described in a supplement to this prospectus.

Investing in our securities involves a high degree of risk. Before investing in our securities, you should carefully read this prospectus and the applicable prospectus supplement, including the section entitled “Risk Factors” beginning on page 1 of this prospectus, the section entitled “Risk Factors” in the applicable prospectus supplement and risk factors in our periodic reports and other information filed with the Securities and Exchange Commission.

These securities are not deposits or obligations of a bank or savings association and are not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus or any accompanying prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is August 3, 2018.

TABLE OF CONTENTS

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ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission (the “SEC”) utilizing a “shelf” registration process. Under this shelf registration process, we may offer and sell the securities described in this prospectus in one or more offerings. This prospectus provides you with only a general description of the securities that we may offer. Each time we offer our securities, we will provide a prospectus supplement containing specific information about the terms of the securities being offered. That prospectus supplement may include a discussion of any risk factors or other special considerations that apply to those securities. The prospectus supplement and any related free writing prospectus may also add, update or change information contained in this prospectus. If there is any inconsistency between the information in this prospectus and in a prospectus supplement or free writing prospectus, you should rely on the information in that prospectus supplement or free writing prospectus, as applicable. You should read this prospectus, any prospectus supplement and any related free writing prospectus together with additional information described below under the heading “Where You Can Find More Information” and “Incorporation of Certain Documents by Reference.”

You should rely only on the information contained or incorporated by reference in this prospectus, any prospectus supplement and any related free writing prospectus. We have not authorized anyone to provide you with different information. We are not making offers to sell the securities in any jurisdiction in which an offer or solicitation is not authorized or in which the person making such offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation.

The rules of the SEC allow us to incorporate by reference information into this prospectus. The information incorporated by reference is considered to be a part of this prospectus, and information that we file later with the SEC will automatically update and supersede this information.

You should not assume that the information in this prospectus, any prospectus supplement, any free writing prospectus or any document incorporated by reference is truthful or complete as of any date other than the date indicated on the cover page of the specific document.

Unless otherwise indicated or unless the context requires otherwise, all references in this prospectus to “Columbia,” the “Company,” “we,” “us,” “our” or similar references mean Columbia Banking System, Inc.

RISK FACTORS

Investing in our securities involves a high degree of risk. Before making an investment decision, you should carefully consider the risk factors incorporated by reference in this prospectus from our Annual Report on Form 10-K for the fiscal year ended December 31, 2017 and other information contained or incorporated by reference in this prospectus and any accompanying prospectus supplements, as the same may be amended and updated from time-to-time by our future filings under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). For more information, see “Where You Can Find More Information” in this prospectus.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, any prospectus supplement and any related free writing prospectus, including information included or incorporated by reference, may contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements include, but are not limited to, statements about our plans, objectives, expectations and intentions that are not historical facts, and other statements identified by words such as “expects,” “anticipates,” “intends,” “plans,” “believes,” “should,” “projects,” “seeks,” “estimates” or the negative version of those words or other comparable words or phrases of a

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future or forward-looking nature. These forward-looking statements are based on current beliefs and expectations of management and are inherently subject to significant business, economic and competitive uncertainties and contingencies, many of which are beyond our control. In addition, these forward-looking statements are subject to assumptions with respect to future business strategies and decisions that are subject to change.

The following factors, among others, could cause actual results of operations to differ materially from the anticipated results or other expectations in the forward-looking statements, including those set forth in this prospectus, any accompanying prospectus supplement, any related free writing prospectus or the documents incorporated by reference, including the “Risk Factors,” “Business” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” sections of our annual or quarterly reports, and other documents we file with the SEC:

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Additional factors that could cause actual results to differ materially from those expressed in the forward-looking statements are discussed in “Risk Factors” above, in our reports filed with the SEC and any risk factors included in any applicable prospectus supplement. We believe the expectations reflected in our forward-looking statements are reasonable, based on information available to us on the date hereof. However, given the described uncertainties and risks, we cannot guarantee our future performance or results of operations, and you should not place undue reliance on these forward-looking statements. We undertake no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required under federal securities laws. The risks described in our other SEC filings and any risk factors included in any applicable prospectus supplement should be considered when reading any forward-looking statements in this document.

WHERE YOU CAN FIND MORE INFORMATION

We are a reporting company and file annual, quarterly and current reports, proxy information and other information with the SEC. You may read and copy such material at the Public Reference Room maintained by the SEC at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for more information on the operation of the Public Reference Room.

The SEC also maintains a website that contains reports, proxy statements and other information about issuers, like us, who file reports electronically with the SEC. The address of that site is www.sec.gov. However, information on this website does not constitute a part of this prospectus.

We have filed with the SEC a registration statement on Form S-3, which registers the securities that we may offer under this prospectus. This prospectus is part of that registration statement and, as permitted by the SEC’s rules, does not contain all the information required to be set forth in the registration statement. We believe that we have included or incorporated by reference all information material to investors in this prospectus, but some details that may be important for specific investment purposes have not been included. For further information, you should read the registration statement and the exhibits filed with or incorporated by reference into the registration statement.

INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The SEC allows us to incorporate by reference information into this prospectus. This means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is considered to be part of this prospectus, except for any information that is superseded by subsequent incorporated documents or by information that is included directly in this prospectus, any prospectus supplement or any related free writing prospectus. We incorporate by reference the documents listed below and any future filings we make with the SEC after the date of this prospectus and until the termination of the offering of securities hereby under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act:

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Nothing in this prospectus shall be deemed to incorporate information furnished to but not filed with the SEC.

You may obtain any of these incorporated documents from us without charge, excluding any exhibits to those documents unless the exhibit is specifically incorporated by reference in such documents, by requesting them from us in writing or by telephone at the following address:

Columbia Banking System, Inc.

1301 A Street

Tacoma, Washington 98402-4200

(253) 305-1900

Attention: Kumi Y. Baruffi, Corporate Secretary

In addition, we maintain a corporate website, www.columbiabank.com. We make available through our website, our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and any amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Exchange Act as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. This reference to our website is for the convenience of investors as required by the SEC and shall not be deemed to incorporate any information on the website into this registration statement, prospectus or any prospectus supplement.

ABOUT COLUMBIA

Columbia Banking System, Inc. is a registered bank holding company whose wholly owned banking subsidiary is Columbia State Bank. Headquartered in Tacoma, Washington, we provide a full range of banking services to small and medium-sized businesses, professionals and individuals throughout Washington, Oregon and Idaho. Our subsidiary, Columbia Trust Company, an Oregon trust company, provides agency, fiduciary and other related trust services with offices in Portland and Salem, Oregon, Tacoma, Washington and Coeur d’Alene, Idaho. Our principal executive offices are located at 1301 A Street, Tacoma, Washington 98402, and our telephone number is (253) 305-1900.

USE OF PROCEEDS

Unless we specify otherwise in a prospectus supplement, we intend to use the net proceeds from our sale of securities under this prospectus for general corporate purposes, which may include:

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Until we use the proceeds for any purpose, we expect to invest them in interest bearing securities.

RATIOS OF EARNINGS TO FIXED CHARGES AND PREFERRED STOCK DIVIDENDS

Our historical ratios of earnings to fixed charges and preferred stock dividends for the periods indicated are set forth in the table below. As of March 31, 2017, we had no shares of preferred stock outstanding.

The ratio of earnings to fixed charges and preferred stock dividends is computed by dividing (1) income from continuing operations before income taxes and fixed charges by (2) total fixed charges and pre-tax earnings required for preferred stock dividends. For purposes of computing these ratios:

DESCRIPTION OF COMMON STOCK WE MAY OFFER

Please note that in this section entitled “Description of Common Stock We May Offer,” references to “holders” mean those who own shares of common stock, registered in their own names, on the books that the registrar or we maintain for this purpose, and not those who own beneficial interests in shares registered in street name or in shares issued in book-entry form through one or more depositaries. Owners of beneficial interests in shares of common stock should also read the section entitled “Legal Ownership and Book-Entry Issuance.”

The following summary description of our common stock is based on the provisions of our Amended and Restated Articles of Incorporation, as amended (the “Articles of Incorporation”), and amended and restated

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bylaws (the “Bylaws”), and the applicable provisions of the Washington Business Corporation Act (the “WBCA”). This description is not complete and is subject to, and is qualified in its entirety by reference to, our Articles of Incorporation, Bylaws (each of which are filed as exhibits to the registration statement of which this prospectus forms a part) and the applicable provisions of the WBCA. For information on how to obtain copies of our Articles of Incorporation and Bylaws, see “Where You Can Find More Information.”

Authorized Capital

As of the date of this prospectus, we have authorized 115,000,000 shares of common stock, no par value per share, 2,000,000 shares of preferred stock, no par value per share. No other classes of capital stock are authorized under our Articles of Incorporation. As of March 31, 2018, there were 73,240,089 shares of common stock issued and outstanding and no shares of preferred stock outstanding.

General

Voting Rights and Liquidation Rights. The holders of our common stock have one vote per share on all matters submitted to a vote of our shareholders. There are no cumulative voting rights for the election of directors. In the event of a liquidation, dissolution or winding up of the Company, the holders of common stock are entitled to share ratably in all assets remaining after payment of liabilities and the liquidation preference of any outstanding preferred stock. Holders of shares of our common stock have no preemptive, subscription, redemption, sinking fund or conversion rights.

Dividends. The holders of our common stock are entitled to receive dividends declared by our board of directors out of funds legally available therefor, subject to preferences that may be applicable to any outstanding series of preferred stock. Holders of debt securities have a priority right to distributions and payment over our common stock. Our ability to pay dividends basically depends on the amount of dividends paid to us by our subsidiaries. The payment of dividends is subject to government regulation, in that regulatory authorities may prohibit banks and bank holding companies from paying dividends in a manner that would constitute an unsafe or unsound banking practice. In addition, a bank may not pay cash dividends if doing so would reduce the amount of its capital below that necessary to meet minimum regulatory capital requirements. State laws also limit a bank’s ability to pay dividends. Accordingly, the dividend restrictions imposed on our subsidiaries by statute or regulation may effectively limit the amount of dividends we can pay.

Transfer Agent. The transfer agent and registrar for our common stock is Broadridge Financial Solutions, Inc.

Antitakeover Effects of Certain Provisions in our Articles, Bylaws and the WBCA

Some provisions of our Articles of Incorporation, our Bylaws and the WBCA may be deemed to have an antitakeover effect and may collectively operate to delay, defer or prevent a tender offer or takeover attempt that a shareholder might consider in his or her best interest, including those attempts that might result in a premium over the market price for the shares held by our shareholders. These provisions include:

Preferred Stock Authorization. As described below, our board of directors, without shareholder approval, has the authority under our Articles of Incorporation to issue preferred stock with rights superior to the rights of the holders of common stock. As a result, preferred stock, while not intended as a defensive measure against takeovers, could be issued quickly and easily, could adversely affect the rights of holders of common stock and could be issued with terms calculated to delay or prevent a change of control of Columbia or make removal of management more difficult.

Articles of Incorporation Limitation on Business Combinations. Our Articles of Incorporation include certain provisions that could make more difficult the acquisition of Columbia by means of a tender offer, a proxy contest, merger or otherwise. These provisions include: (a) certain non-monetary factors that the Columbia board

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of directors may consider when evaluating a takeover offer, as described below, and (b) a requirement that any “Business Combination” (as defined in the Articles of Incorporation) be approved by the affirmative vote of no less than 66 2/3% of the total shares attributable to persons other than a “Control Person” (as defined in the Articles of Incorporation), unless certain conditions are met.

Columbia’s Articles of Incorporation allow the Columbia board of directors to consider non-monetary factors in evaluating certain takeover bids. Specifically, the Articles of Incorporation allow the board of directors, in determining what is in the best interests of Columbia and its shareholders, to consider all relevant factors, including, without limitation, the social and economic effects on its employees, customers, suppliers and other constituents of Columbia and its subsidiaries and on the communities in which Columbia and its subsidiaries operate or are located.

The requirement for “Super-Majority” approval of certain business transactions does not apply if the Columbia board of directors has approved the transaction or if certain other conditions are satisfied relating to non-discrimination among shareholders, receipt of fair value and the mailing of a proxy statement responsive to the requirements of the Exchange Act to Columbia’s public shareholders.

WBCA Requirements. In addition to the provisions contained in Columbia’s Articles of Incorporation, Washington law also requires prior approval by a majority of the board of directors of a target company in certain acquisition transactions. Washington law prohibits corporations that have a class of voting stock registered under the Exchange Act, such as Columbia, from engaging in any “Significant Business Transaction” (defined to include mergers or consolidations, certain sales, termination of 5% or more of a corporation’s employees, sales of assets, liquidation or dissolution, and other specified transactions) for a period of five years after a person or group acquires 10% or more of a corporation’s outstanding voting stock, unless the acquisition is approved in advance by a majority vote of the board of directors, or, at or subsequent to the acquiring person or group’s acquisition of shares of the corporation, such Significant Business Transaction is approved by a majority vote of the target corporation’s board of directors and authorized by the affirmative vote of at least two-thirds of the corporation’s outstanding voting shares (except those beneficially owned or under voting control of the acquiring person).

Amendment of Articles of Incorporation and Bylaws. Under the WBCA, the Articles of Incorporation of Columbia, as a “public” company, may be amended upon the affirmative vote of the holders of a majority of Columbia’s outstanding voting stock. However, the provisions of Article 9 of Columbia’s Articles of Incorporation, relating to Business Combinations as described above, may not be amended or repealed without the affirmative vote of holders of not less than 66 2/3% of Columbia’s outstanding voting stock. The Columbia board of directors may make certain amendments, as listed in the WBCA, to the Articles of Incorporation without shareholder approval. The Columbia board of directors may, by a majority vote, amend or repeal Columbia’s Bylaws.

Proposals and Nominations. The Bylaws provide that no nominations for director of Columbia by any person other than the Columbia board of directors or any committee thereof may be presented to any meeting of stockholders unless the person making the nomination is a record stockholder and has timely delivered a written notice to the Secretary of Columbia which complies with the information requirements contained in the Bylaws. In general, to be timely notice must be received by our Secretary during the period beginning 150 days and ending 120 days before the anniversary of the last annual meeting. However, if the date of the upcoming annual meeting is more than 30 days before or more than 60 days after the anniversary of the last annual meeting, notice must be received by our Secretary during the period beginning 150 days before the upcoming annual meeting and ending on the later of 120 days before the upcoming annual meeting or, if the first public announcement of the date of the upcoming annual meeting is less than 100 days prior to the date of such annual meeting, 10 days after the first public announcement of such meeting date.

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DESCRIPTION OF PREFERRED STOCK WE MAY OFFER

Please note that in this section entitled “Description of Preferred Stock We May Offer,” references to “holders” mean those who own shares of preferred stock registered in their own names, on the books that the registrar or we maintain for this purpose, and not those who own beneficial interests in shares registered in street name or in shares issued in book-entry form through one or more depositaries. Owners of beneficial interests in shares of preferred stock should also read the section entitled “Legal Ownership and Book-Entry Issuance.”

The following description summarizes the material provisions of the preferred stock we may offer. This description is not complete and is subject to, and is qualified in its entirety by reference to our Articles of Incorporation, Bylaws and the applicable provisions of the WBCA. The specific terms of any series of preferred stock will be described in the applicable prospectus supplement. Any series of preferred stock we issue will be governed by our Articles of Incorporation (as amended and in effect as of the date of such issuance) and by the articles of amendment related to that series. We will file the articles of amendment with the SEC and incorporate it by reference as an exhibit to our registration statement at or before the time we issue any preferred stock of that series of authorized preferred stock.

General

Under our Articles of Incorporation, our board of directors has the authority, without any further vote or action by our shareholders, to issue up to 2,000,000 shares of preferred stock in one or more series and to fix, determine or amend the relative rights and preferences of the shares of any series so established, within the limitations set forth in the WBCA, relating to the preferences, limitations, voting powers and relative rights thereof, including, but not limited to:

The applicable prospectus supplement will describe the specific dividend, liquidation, redemption, voting and any conversion rights relating to the particular series of the preferred stock it offers, including among other things dividend rates; dividend periods; whether dividends will be cumulative or noncumulative; the terms upon which we may, or must, redeem such preferred stock; rights upon liquidation; and voting rights.

Unless the applicable prospectus supplement specifies otherwise, the preferred stock will have no preemptive rights to subscribe for any additional securities that we may issue in the future, which means that holders of shares of preferred stock will have no right, as holders of shares of preferred stock, to buy any portion of those issued securities.

DESCRIPTION OF DEPOSITARY SHARES WE MAY OFFER

Please note that in this section entitled “Description of the Depositary Shares We May Offer,” references to “holders” mean those who own depositary shares registered in their own names, on the books that the registrar or we maintain for this purpose, and not those who own beneficial interests in shares registered in street name or in shares issued in book-entry form through one or more depositaries. Owners of beneficial interests in depositary shares should also read the section entitled “Legal Ownership and Book-Entry Issuance.”

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This section outlines some of the provisions of the deposit agreement to govern any depositary shares, the depositary shares themselves and the depositary receipts. This information may not be complete in all respects and is qualified entirely by reference to the relevant deposit agreement and depositary receipts with respect to the depositary shares related to any particular series of preferred stock. The specific terms of any series of depositary shares will be described in the applicable prospectus supplement. If so described in the prospectus supplement, the terms of that series of depositary shares may differ from the general description of terms presented below.

While the deposit agreement relating to a particular series of preferred stock may have provisions applicable solely to that series of preferred stock, all deposit agreements relating to preferred stock we issue will include the following provisions:

Dividends and Other Distributions

Each time we pay a cash dividend or make any other type of cash distribution with regard to preferred stock of an applicable series, the depositary will distribute to the holder of record of each depositary share relating to that series of preferred stock an amount equal to the dividend or other distribution per depositary share the depositary receives. If there is a distribution of property other than cash, the depositary either will distribute the property to the holders of depositary shares in proportion to the depositary shares held by each of them, or the depositary will, if we approve, sell the property and distribute the net proceeds to the holders of the depositary shares in proportion to the depositary shares held by them.

Withdrawal of Preferred Stock

A holder of depositary shares will be entitled to receive, upon surrender of depositary receipts representing depositary shares, the number of whole or fractional shares of the applicable series of preferred stock, and any money or other property, to which the depositary shares relate.

Redemption of Depositary Shares

Whenever we redeem shares of applicable preferred stock held by a depositary, the depositary will be required to redeem, on the same redemption date, depositary shares constituting, in total, the number of shares of preferred stock held by the depositary which we redeem, subject to the depositary’s receiving the redemption price of those shares of preferred stock. If fewer than all the depositary shares relating to a series are to be redeemed, the depositary shares to be redeemed will be selected by lot or by another method we determine to be equitable.

Voting

Any time we send a notice of meeting or other materials relating to a meeting to the holders of an applicable series of preferred stock to which depositary shares relate, we will provide the depositary with sufficient copies of those materials so they can be sent to all holders of record of the applicable depositary shares, and the depositary will send those materials to the holders of record of the depositary shares on the record date for the meeting. The depositary will solicit voting instructions from holders of depositary shares and will vote or not vote the applicable preferred stock to which the depositary shares relate in accordance with those instructions.

Liquidation Preference

Upon our liquidation, dissolution or winding up, the holder of each depositary share will be entitled to what the holder of the depositary share would have received if the holder had owned the number of shares (or fraction of a share) of applicable preferred stock which is represented by the applicable depositary share.

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Conversion

If shares of an applicable series of preferred stock are convertible into common stock or other of our securities or property, holders of depositary shares relating to that series of preferred stock will, if they surrender depositary receipts representing depositary shares and appropriate instructions to convert them, receive the shares of common stock or other securities or property into which the number of shares (or fractions of shares) of applicable preferred stock to which the depositary shares relate could at the time be converted.

Amendment and Termination of a Deposit Agreement

We and the depositary may amend a deposit agreement and the form of depositary receipt, except that an amendment which materially and adversely affects the rights of holders of depositary shares, or would be materially and adversely inconsistent with the rights granted to the holders of the applicable preferred stock to which they relate, must be approved by holders of at least a majority of the outstanding depositary shares. No amendment will impair the right of a holder of depositary shares to surrender the depositary receipts evidencing those depositary shares and receive the applicable preferred stock to which they relate, except as required to comply with law. We may terminate a deposit agreement at any time, as long as the depositary mails notice of termination to the record holders of depositary shares then outstanding at least 30 days prior to the date fixed for termination. Upon termination, the depositary shall deliver to each holder of depositary receipts, upon surrender of the depositary receipts held by such holder, such number of whole or fractional shares of preferred stock as are represented by the depositary shares evidenced by such depositary receipts, together with any other property held by the depositary with respect to such depositary receipt. A deposit agreement will automatically terminate if:

DESCRIPTION OF DEBT SECURITIES WE MAY OFFER

Please note that in this section entitled “Description of Debt Securities We May Offer,” references to “holders” mean those who own debt securities registered in their own names on the books that we or the trustee maintain for this purpose, and not those who own beneficial interests in debt securities registered in street name or in debt securities issued in book-entry form through one or more depositaries. Owners of beneficial interests in the debt securities should also read the section entitled “Legal Ownership and Book-Entry Issuance.”

The following description summarizes the material provisions of the senior debt indenture, the subordinated debt indenture and the debt securities to be issued under the senior debt indenture and subordinated debt indenture, respectively. This description is not complete and is subject to, and is qualified in its entirety by reference to, the indenture under which the debt securities are issued and the Trust Indenture Act of 1939, as amended (the “Trust Indenture Act”). The specific terms of any series of debt securities will be described in the applicable prospectus supplement, and may differ from the general description of the terms presented below. The senior debt security indenture and the form of subordinated debt security indenture have been filed as exhibits to our SEC registration statement relating to this prospectus. References to our senior debt indenture and subordinated debt indenture in this section mean the forms of indenture filed as exhibits to the registration statement of which this prospectus forms a part, such forms of indenture not having been executed as of the date of this prospectus.

Debt Securities May Be Senior or Subordinated

We may issue senior or subordinated debt securities. Except as otherwise described in the applicable prospectus supplement, neither the senior debt securities nor the subordinated debt securities will be secured by

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any property or assets of ours or any of our subsidiaries. Thus, by owning a debt security, you are an unsecured creditor of Columbia.

The senior debt securities will be issued under a senior debt indenture described below (a form of which is filed as an exhibit to the registration statement of which this prospectus forms a part), as it may be supplemented or amended from time-to-time, and will rank equally with all of our other senior unsecured and unsubordinated debt.

The subordinated debt securities will be issued under a subordinated debt indenture described below (a form of which is filed as an exhibit to the registration statement of which this prospectus forms a part), as it may be supplemented or amended from time-to-time, and will be subordinate in right of payment to all of our “senior indebtedness,” as defined in the subordinated debt indenture, as it may be supplemented or amended from time-to-time. The prospectus supplement for any series of subordinated debt securities or the information incorporated in this prospectus by reference will indicate the approximate amount of senior indebtedness outstanding as of the end of our most recent fiscal quarter. Neither indenture will limit our ability to incur additional senior indebtedness, unless otherwise described in the prospectus supplement relating to any series of debt securities. Our senior indebtedness is, and any additional senior indebtedness will be, structurally subordinated to the indebtedness of our subsidiaries. See “—Our Debt Securities Are Structurally Subordinated to Indebtedness of Our Subsidiaries” below.

When we refer to “debt securities” in this prospectus, we mean both the senior debt securities and the subordinated debt securities.

The Senior Debt Indenture and the Subordinated Debt Indenture

The senior debt securities and the subordinated debt securities will each be governed by a document called an indenture – the senior debt indenture, in the case of the senior debt securities, and the subordinated debt indenture, in the case of the subordinated debt securities. Each indenture will be a contract between us and the trustee under the indentures. The indentures will be substantially identical, except for the provisions relating to subordination, which will be included only in the subordinated debt indenture. At or prior to the time of offering of our debt securities, we will appoint a trustee under the applicable indenture. We will identify who that trustee is in the applicable prospectus supplement.

The trustee under each indenture has two main roles:

When we refer to the indenture or the trustee with respect to any debt securities, we mean the indenture under which those debt securities will be issued and the trustee under that indenture.

We May Issue Many Series of Debt Securities

We may issue as many distinct series of debt securities under either debt indenture as we wish. This section of the prospectus summarizes terms of the securities that will apply generally to all series. The provisions of each indenture will allow us not only to issue debt securities with terms different from those of debt securities previously issued under that indenture, but also to “reopen” a previous issue of a series of debt securities and issue additional debt securities of that series. We will describe most of the financial and other specific terms of a series, whether it be a series of the senior debt securities or subordinated debt securities, in the applicable prospectus supplement accompanying this prospectus. Those terms may vary from the terms described here.

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As you read this section of the prospectus, please remember that the specific terms of your debt security will be described in an accompanying prospectus supplement relating to your debt security and, if applicable, modify or replace the general terms described in this section. If there are any differences between the accompanying prospectus supplement and this prospectus, the prospectus supplement will control. Thus, the statements we make in this section may not apply to your debt security.

When we refer to a series of debt securities, we mean a series issued under the applicable indenture. When we refer to the prospectus supplement, we mean the prospectus supplement describing the specific terms of the debt security you purchase.

Amounts That We May Issue

Neither indenture will limit the aggregate amount of debt securities that we may issue or the number of series or the aggregate amount of any particular series. We may issue debt securities and other securities up to the aggregate amount authorized by us for each series, at any time without your consent and without notifying you.

The indentures and the debt securities will not limit our ability to incur other indebtedness or to issue other securities, unless otherwise described in the prospectus supplement relating to any series of debt securities. Also, we will not be subject to financial or similar restrictions by the terms of the debt securities, unless otherwise described in the prospectus supplement relating to any series of debt securities.

Principal Amount, Stated Maturity and Maturity

The principal amount of a debt security means the principal amount payable at its stated maturity, unless that amount is not determinable, in which case the principal amount of a debt security is its face amount. Any debt securities owned by us or any of our affiliates will not be deemed to be outstanding for certain determinations under the indenture.

The term “stated maturity” with respect to any debt security means the day on which the principal amount of the debt security is scheduled to become due. The principal may become due sooner, by reason of redemption or acceleration after a default or otherwise in accordance with the terms of the debt security. The day on which the principal actually becomes due, whether at the stated maturity or earlier, is called the “maturity” of the principal.

We also use the terms “stated maturity” and “maturity” to refer to the days when other payments become due. For example, we refer to a regular interest payment date when an installment of interest is scheduled to become due as the “stated maturity” of that installment.

When we refer to the “stated maturity” or the “maturity” of a debt security without specifying a particular payment, we mean the stated maturity or maturity, as the case may be, of the principal.

Our Debt Securities Are Structurally Subordinated to Indebtedness of Our Subsidiaries

Because our assets consist principally of ownership interests in Columbia State Bank, through which we own our assets and conduct our businesses, our right to participate as an equity holder in any distribution of assets of any of our subsidiaries upon the subsidiary’s liquidation or otherwise, and thus the ability of our security holders to benefit from the distribution, is junior to creditors of the subsidiary, except to the extent that any claims we may have as a creditor of the subsidiary are recognized. If we are recognized as a creditor of a subsidiary, our claims would still be subordinate to any security interest in the assets of that subsidiary and any indebtedness of that subsidiary senior to that held by us. Claims from creditors (other than us) on subsidiaries may include long-term and medium-term debt and substantial obligations related to deposit liabilities, federal funds purchased, securities sold under repurchase agreements and other short-term borrowings.

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We may also guarantee some obligations of our subsidiaries. Any liability we may have for our subsidiaries’ obligations could reduce our assets that are available to satisfy our direct creditors, including investors in our debt securities.

This Section Is Only a Summary

The indentures and any associated documents, including your debt security, will contain the full legal text of the matters described in this section and the prospectus supplement. Forms of the indentures are filed with the SEC as exhibits to the registration statement on Form S-3 of which this prospectus forms a part.

This section and the applicable prospectus supplement summarize the material terms of the indentures and your debt security. They do not, however, describe every aspect of the indentures and your debt security. For example, in this section and the applicable prospectus supplement, we use terms that have been given special meaning in the indentures, but we describe the meaning for only the more important of those terms.

Governing Law

The indentures and the debt securities will be governed by New York law.

Currency of Debt Securities

Amounts that become due and payable on a debt security in cash will be payable in a currency, currencies or currency units specified in the accompanying prospectus supplement. We refer to this currency, currencies or currency units as a “specified currency.” The specified currency for a debt security will be U.S. dollars, unless the prospectus supplement states otherwise. Some debt securities may have different specified currencies for principal and interest. You will have to pay for your debt securities by delivering the requisite amount of the specified currency for the principal to us or the underwriters, agents or dealers that we name in the prospectus supplement, unless other arrangements have been made between you and us or you and that firm. We will make payments on a debt security in the specified currency, except as described below under “—Payment Mechanics for Debt Securities.”

Form of Debt Securities

We will issue each debt security in global—i.e., book-entry—form only, unless we specify otherwise in the applicable prospectus supplement. Debt securities in book-entry form will be represented by a global security registered in the name of a depositary, which we describe below under “Legal Ownership and Book-Entry Issuance—What is a Global Security?,” which will be the holder of all the debt securities represented by that global security. Those who own beneficial interests in a global debt security will do so through participants in the depositary’s securities clearance system, and the rights of these indirect owners will be governed solely by the applicable procedures of the depositary and its participants. We describe book-entry securities below in the section entitled “Legal Ownership and Book-Entry Issuance.”

In addition, we will issue each debt security in fully registered form, without coupons, unless we specify otherwise in the applicable prospectus supplement.

Information in the Prospectus Supplement

A prospectus supplement will describe the specific terms of a particular series of debt securities, which will include some or all of the following:

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Redemption and Repayment

Unless otherwise indicated in the applicable prospectus supplement, a debt security will not be entitled to the benefit of any sinking fund—that is, we will not deposit money on a regular basis into any separate custodial account to repay the debt securities. In addition, we will not be entitled to redeem a debt security before its stated maturity unless the applicable prospectus supplement specifies a redemption commencement date. You will not be entitled to require us to buy a debt security from you before its stated maturity unless the applicable prospectus supplement specifies one or more repayment dates.

If your applicable prospectus supplement specifies a redemption commencement date or a repayment date, it will also specify one or more redemption prices or repayment prices, which may be expressed as a percentage of the principal amount of the debt security. It may also specify one or more redemption periods during which the redemption prices relating to a redemption of debt securities during those periods will apply.

If we redeem less than all the debt securities of any series, we will, at least 60 days before the redemption date set by us or any shorter period that is satisfactory to the trustee, notify the trustee of the redemption date, of the principal amount of debt securities to be redeemed and if applicable, of the tenor of the debt securities to be redeemed. The trustee will select from the outstanding securities of the series the particular debt securities to be redeemed not more than 60 days before the redemption date.

If the applicable prospectus supplement specifies a redemption commencement date, the debt security will be redeemable at our option at any time on or after that date or at a specified time or times. If we redeem the debt security, we will do so at the specified redemption price, together with interest accrued to the redemption date. If different prices are specified for different redemption periods, the price we pay will be the price that applies to the redemption period during which the debt security is redeemed.

If the applicable prospectus supplement specifies a repayment date, the debt security will be repayable at the holder’s option on the specified repayment date at the specified repayment price, together with interest accrued to the repayment date.

If we exercise an option to redeem any debt security, we will give to the holder written notice of the principal amount of the debt security to be redeemed, except as otherwise described in the applicable prospectus supplement, not less than 30 days nor more than 60 days before the applicable redemption date. We will give the notice in the manner described below under “—Notices.”

If a debt security represented by a global debt security is subject to repayment at the holder’s option, the depositary or its nominee, as the holder, will be the only person that can exercise the right to repayment. Any indirect owners who own beneficial interests in the global debt security and wish to exercise a repayment right must give proper and timely instructions to their banks or brokers through which they hold their interests, requesting that they notify the depositary to exercise the repayment right on their behalf. Different firms have different deadlines for accepting instructions from their customers, and you should take care to act promptly enough to ensure that your request is given effect by the depositary before the applicable deadline for exercise.

Street name and other indirect owners should contact their banks or brokers for information about how to exercise a repayment right in a timely manner.

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We or our affiliates may purchase debt securities from investors who are willing to sell from time-to-time, either in the open market at prevailing prices or in private transactions at negotiated prices. Debt securities that we or they purchase may, at our discretion, be held, resold or canceled.

Mergers and Similar Transactions

We will generally be permitted to merge or consolidate with another entity. We will also be permitted to sell our assets substantially as an entirety to another entity. With regard to any series of debt securities, however, unless otherwise indicated in the applicable prospectus supplement, we will not be permitted to take any of these actions unless all the following conditions are met:

If the conditions described above are satisfied with respect to the debt securities of any series, we will not need to obtain the approval of the holders of those debt securities in order to merge or consolidate or to sell our assets. Also, these conditions will apply only if we wish to merge or consolidate with another entity or sell our assets substantially as an entirety to another entity. We will not need to satisfy these conditions if we enter into other types of transactions, including any transaction in which we acquire the stock or assets of another entity, any transaction that involves a change of control of us but in which we do not merge or consolidate and any transaction in which we sell assets in an amount that does not constitute a sale of our assets substantially as an entirety.

Subordination Provisions

Holders of subordinated debt securities should recognize that contractual provisions in the subordinated debt indenture may prohibit us from making payments on those securities.

Our obligations under subordinated debt securities will be subordinated to the claims of all of our then-existing general creditors other than trade creditors, including claims of holders of the senior debt securities and Columbia’s other senior creditors. Subject to applicable law, in any voluntary or involuntary insolvency or bankruptcy proceedings, or any receivership, liquidation, reorganization or other similar proceeding involving us or our assets or any liquidation or winding-up of or relating to us, to the extent applicable, the rights of the holder of any subordinated debt security shall be subordinated in right of payment to the claims of holders of senior indebtedness. The subordinated debt indenture defines “senior indebtedness” as all amounts due on obligations to general creditors, whether outstanding or subsequently incurred or created, including:

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However, “senior debt” excludes any indebtedness or monetary obligations to trade creditors created or assumed by us.

Even if the subordination provisions prevent us from making any payment when due on the subordinated debt securities of any series, we will be in default on our obligations under that series if we do not make the payment when due. This means that the trustee under the subordinated debt indenture and the holders of that series will be able to take action against us, but they will not receive any money until the claims of the holders of senior debt have been fully satisfied.

Defeasance and Covenant Defeasance

The provisions for full defeasance and covenant defeasance described below will apply to each senior and subordinated debt security if so indicated in the applicable prospectus supplement.

Full Defeasance. If there is a change in federal income tax law, as described below, we will be able to legally release ourselves from all payment and other obligations on any debt securities. This is called full defeasance. For us to do so, each of the following must occur:

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If we ever fully defeased your debt security, you would have to rely solely on the trust deposit for payments on your debt security. You would not be able to look to us for payment if there was any shortfall.

Covenant Defeasance. Under current federal income tax law, we will be able to make the same type of deposit described above and be released from the restrictive covenants relating to your debt security listed in the bullets below and any additional restrictive covenants that may be described in the prospectus supplement. This is called covenant defeasance. In that event, you would lose the protection of those restrictive covenants. In order to achieve covenant defeasance for any debt securities, we must take the same steps as are required for full defeasance.

If we accomplish covenant defeasance with regard to your debt security, the following provisions of the applicable indenture and your debt security would no longer apply:

If we accomplish covenant defeasance on your debt security, we must still repay your debt security if there is any shortfall in the trust deposit. You should note, however, that if one of the remaining events of default occurred, such as our bankruptcy, and your debt security became immediately due and payable, there may be a shortfall. Depending on the event causing the default, you may not be able to obtain payment of the shortfall.

Default, Remedies and Waiver of Default

You will have special rights if an event of default with respect to your series of debt securities occurs and is continuing, as described in this subsection.

Events of Default and Certain Remedies under the Senior Indenture. Unless the applicable prospectus supplement says otherwise, when we refer to an event of default with respect to any series of senior debt securities, we mean any of the following:

If an event of default described in any of the bullet point paragraphs (other than the fifth bullet point paragraph) above occurs and is continuing, then and in each such case either the trustee or the holders of not less than 25% in principal amount of the senior debt securities of any such series then outstanding (each such series treated as a separate class), may declare the principal amount (or, if the senior debt securities of such series are original issue discount securities, such portion of the principal amount as may be specified in the terms of such series) of all the senior debt securities of such series to be due and payable immediately, and upon any such declaration the same shall become immediately due and payable. If an event of default described in the fifth

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bullet point paragraph above occurs and is continuing, then the principal amount (or, if the senior debt securities of such series are original issue discount securities, such portion of the principal amount as may be specified in the terms of such series) of all senior debt securities of such series shall be and become immediately due and payable, without any notice or other action by the trustee or any holder, to the fullest extent permitted by law.

Events of Default and Certain Remedies Under the Subordinated Indenture. Unless the applicable prospectus supplement says otherwise, when we refer to an event of default with respect to any series of subordinated debt securities, we mean any of the following:

If an event of default described in the fifth bullet point paragraph above occurs and is continuing, then and in each such case either the trustee or the holders of not less than 25% in principal amount of the subordinated debt securities of any such series then outstanding (each such series treated as a separate class), may declare the principal amount (or, if the subordinated debt securities of any such series are original issue discount securities, such portion of the principal amount as may be specified in the terms of such series) of all the subordinated debt securities of such series to be due and payable immediately, and upon any such declaration the same shall become immediately due and payable.

Unless otherwise expressly provided in the applicable prospectus supplement, there is no right of acceleration under the subordinated indenture upon the occurrence of an event of default described in any of the bullet point paragraphs (other than the fifth bullet point paragraph) above. However, if a default occurs, the trustee may proceed to enforce any covenant and other rights of the holders of the subordinated debt securities.

Certain Remedies If an Event of Default Occurs. If you are the holder of a subordinated debt security, all the remedies available upon the occurrence of an event of default under the subordinated debt indenture will be subject to the restrictions on the subordinated debt securities described above under “—Subordination Provisions.”

The situations described above are called an acceleration of the maturity of the affected series of debt securities. If the maturity of any series is accelerated, a judgment for payment has not yet been obtained, we pay or deposit with the trustee an amount sufficient to pay all amounts due on the securities of the series, and all events of default with respect to the series, other than the nonpayment of the accelerated principal, have been cured or waived, then the holders of a majority in principal amount of the outstanding debt securities of that series may cancel the acceleration for the entire series.

If an event of default occurs, the trustee will have special duties. In that situation, the trustee will be obligated to use those of its rights and powers under the relevant indenture, and to use the same degree of care and skill in so doing, that a prudent person would use in that situation in conducting his or her own affairs.

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Except as described in the prior paragraph, the trustee will not be required to take any action under the relevant indenture at the request of any holders unless the holders offer the trustee reasonable protection from expenses and liability. This is called an indemnity. If the trustee is provided with an indemnity reasonably satisfactory to it, the holders of a majority in principal amount of all debt securities of the relevant series may direct the time, method and place of conducting any lawsuit or other formal legal action seeking any remedy available to the trustee with respect to that series. These majority holders may also direct the trustee in performing any other action under the applicable indenture with respect to the debt securities of that series.

Before you are permitted to bypass the trustee and bring your own lawsuit or other formal legal action or take other steps to enforce your rights or protect your interests relating to any debt security, all of the following must occur:

You will be entitled at any time, however, to bring a lawsuit for the payment of money due on your debt security on or after its due date.

Waiver of Default. The holders of a majority in principal amount of the outstanding debt securities of a series may waive a default for all debt securities of that series. If this happens, the default will be treated as if it has not occurred. No one can waive a payment default on your debt security or a covenant or provision of the indenture that cannot be modified or amended without the consent of the holder of each outstanding debt security of the series, however, without the approval of the particular holder of that debt security.

We Will Give the Trustee Information About Defaults Annually. We will furnish to each trustee every year a written statement of two of our officers certifying that to their knowledge we are in compliance with the applicable indenture and the debt securities issued under it, or else specifying any default under the indenture.

Book-entry and other indirect owners should consult their banks or brokers for information on how to give notice or direction to or make a request of the trustee and how to declare or cancel an acceleration of the maturity. Book-entry and other indirect owners are described below in the section entitled “Legal Ownership and Book-Entry Issuance.”

Changes of the Indentures Requiring Each Holder’s Approval

There are certain changes that will not be permitted without the approval of each holder of a debt security affected by the change under a particular indenture. Here is a list of those types of changes:

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Modification of Subordination Provisions

We will not be permitted to amend the subordinated debt indenture to alter the subordination of any outstanding subordinated debt securities without the written consent of each holder of senior debt then outstanding who would be adversely affected. In addition, we will not be permitted to modify the subordination provisions of the subordinated debt indenture in a manner that would adversely affect the outstanding subordinated debt securities of any one or more series in any material respect, without the consent of the holders of a majority in aggregate principal amount of all affected series, voting together as one class.

Changes of the Indentures Not Requiring Approval

Other types of changes will not require any approval by holders of the debt securities of an affected series. These changes include modifications or amendments for the following purposes:

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Changes of the Indentures Requiring Majority Approval

Any other change to a particular indenture and the debt securities issued under that indenture will require the following approval:

The same majority approval would be required for us to obtain a waiver of any of our covenants in either indenture. Our covenants include the promises we make about merging and similar transactions, which we describe above under “—Mergers and Similar Transactions.” If the requisite holders approve a waiver of a covenant, we will not have to comply with it. The holders, however, will not be permitted to approve a waiver of any provision in a particular debt security, or in the applicable indenture as it affects that debt security, that we cannot change without the approval of the holder of that debt security as described above under “—Changes of the Indentures Requiring Each Holder’s Approval,” unless that holder approves the waiver.

Book-entry and other indirect owners should consult their banks or brokers for information on how approval may be granted or denied if we seek to change an indenture or any debt securities or request a waiver.

Special Rules for Action by Holders

When holders take any action under either debt indenture, such as giving a notice of default, declaring an acceleration, approving any change or waiver or giving the trustee an instruction, we will apply the following rules.

Only Outstanding Debt Securities Are Eligible. Only holders of outstanding debt securities of the applicable series will be eligible to participate in any action by holders of debt securities of that series. Also, we will count only outstanding debt securities in determining whether the various percentage requirements for taking action have been met. For these purposes, a debt security will not be “outstanding”:

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Eligible Principal Amount of Some Debt Securities. In some situations, we may follow special rules in calculating the principal amount of a debt security that is to be treated as outstanding for the purposes described above. This may happen, for example, if the principal amount is payable in a non-U.S. dollar currency, increases over time or is not to be fixed until maturity.

For any debt security of the kind described below, we will decide how much principal amount to attribute to the debt security as follows:

Determining Record Dates for Action by Holders. We will generally be entitled to set any day as a record date for the purpose of determining the holders that are entitled to take action under either indenture. In certain limited circumstances, only the trustee will be entitled to set a record date for action by holders. If we or the trustee set a record date for an approval or other action to be taken by holders, that vote or action may be taken only by persons or entities who are holders on the record date and must be taken during the period that we specify for this purpose, or that the trustee specifies if it sets the record date. We or the trustee, as applicable, may shorten or lengthen this period from time-to-time. This period, however, may not extend beyond the 180th day after the record date for the action. In addition, record dates for any global debt security may be set in accordance with procedures established by the depositary from time-to-time. Accordingly, record dates for global debt securities may differ from those for other debt securities.

Form, Exchange and Transfer of Debt Securities. Unless we indicate otherwise in the applicable prospectus supplement, the debt securities will be issued:

Holders will be permitted to exchange their debt securities for debt securities of the same series in any authorized denominations, as long as the total principal amount is not changed.

Holders will be permitted to exchange or transfer their debt securities at the office of the trustee. They will also be permitted to replace lost, stolen, destroyed or mutilated debt securities at that office. We anticipate appointing the trustee to act as our agent for registering debt securities in the names of holders and transferring and replacing debt securities.

Holders will not be required to pay a service charge to transfer or exchange their debt securities, but they may be required to pay for any tax or other governmental charge associated with the registration, exchange or transfer. The transfer or exchange, and any replacement, will be made only if our transfer agent is satisfied with the holder’s proof of legal ownership. The transfer agent may require an indemnity before replacing any debt securities.

If a debt security is issued as a global debt security, only the depositary—e.g., DTC, Euroclear Bank S.A./N.V., as operator of the Euroclear system (“Euroclear”) and Clearstream Banking S.A. (“Clearstream”)—will be entitled to transfer and exchange the debt security as described in this subsection, since the depositary will be the sole holder of the debt security.

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The rules for exchange described above apply to exchange of debt securities for other debt securities of the same series and kind. If a debt security is convertible into or exchangeable for our common stock or preferred stock, the rules governing that type of exchange will be described in the applicable prospectus supplement.

Payment Mechanics for Debt Securities.

Who Receives Payment?

If interest is due on a debt security on an interest payment date, we will pay the interest to the person in whose name the debt security is registered at the close of business on the regular record date relating to the interest payment date as described below under “—Payment and Record Dates for Interest.” If interest is due at maturity but on a day that is not an interest payment date, we will pay the interest to the person entitled to receive the principal of the debt security. If principal or another amount besides interest is due on a debt security at maturity, we will pay the amount to the holder of the debt security against surrender of the debt security at a proper place of payment or, in the case of a global debt security, in accordance with the applicable policies of the depositary, DTC, Euroclear or Clearstream, as applicable.

Payment and Record Dates for Interest

The dates on which interest will be payable will be specified in the applicable prospectus supplement. The regular record date relating to an interest payment date for any fixed-rate debt security or floating-rate debt security will be on or about the 15th calendar day before that interest payment date. These record dates will apply regardless of whether a particular record date is a “business day,” as defined below. For the purpose of determining the holder at the close of business on a regular record date when business is not being conducted, the close of business will mean 5:00 P.M., New York City time, on that day.

Business Day. The term “business day” will mean, with respect to the debt securities of a series, a Monday, Tuesday, Wednesday, Thursday or Friday that is not a day on which banking institutions in the place of payment for the debt securities of that series are authorized or obligated by law or executive order to close and that satisfies any other criteria specified in the applicable prospectus supplement.

How We Will Make Payments Due in U.S. Dollars

We will follow the practice described in this subsection when paying amounts due in U.S. dollars. Payments of amounts due in other currencies will be made as described in the next subsection.

Payments on Global Debt Securities. We will make payments on a global debt security in accordance with the applicable policies of the depositary as in effect from time-to-time. Under those policies, we will make payments directly to the depositary, or its nominee, and not to any indirect owners who own beneficial interests in the global debt security. An indirect owner’s right to receive those payments will be governed by the rules and practices of the depositary and its participants, as described below in the section entitled “Legal Ownership and Book-Entry Issuance—What Is a Global Security?”

Payments on Non-Global Debt Securities. We will make payments on a debt security in non-global, registered form as follows. We will pay interest that is due on an interest payment date by check mailed on the interest payment date to the holder at his or her address shown on the trustee’s records as of the close of business on the regular record date. We will make all other payments by check to the paying agent described below, against surrender of the debt security. All payments by check will be made in next-day funds—i.e., funds that become available on the day after the check is cashed.

Alternatively, if a non-global debt security has a face amount of at least $1,000,000 and the holder asks us to do so, we will pay any amount that becomes due on the debt security by wire transfer of immediately available

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funds to an account at a bank in New York City, on the due date. To request a wire payment, the holder will be required to give the paying agent appropriate wire transfer instructions at least five business days before the requested wire payment is due. In the case of any interest payment due on an interest payment date, the instructions will be required to be given by the person or entity who is the holder on the relevant regular record date. In the case of any other payment, payment will be made only after the debt security is surrendered to the paying agent. Any wire instructions, once properly given, will remain in effect unless and until new instructions are given in the manner described above.

Book-entry and other indirect owners should consult their banks or brokers for information on how they will receive payments on their debt securities.

How We Will Make Payments Due in Other Currencies

We will follow the practice described in this subsection when paying amounts that are due in a specified currency other than U.S. dollars.

Payments on Global Debt Securities. We will make payments on a global debt security in accordance with the applicable policies as in effect from time-to-time of the depositary, which will be DTC, Euroclear or Clearstream. Unless we specify otherwise in the applicable prospectus supplement, DTC will be the depositary for all debt securities in global form. We understand that DTC’s policies, as currently in effect, are as follows.

Unless otherwise indicated in the applicable prospectus supplement, if you are an indirect owner of global debt securities denominated in a specified currency other than U.S. dollars and if you have the right to elect to receive payments in that other currency and do so elect, you will be required to notify the participant through which your interest in the global debt security is held of your election:

Your participant will be required, in turn, to notify DTC of your election on or before the third DTC business day after that regular record date, in the case of a payment of interest, and on or before the 12th DTC business day prior to the stated maturity, or on the redemption or repayment date if your debt security is redeemed or repaid earlier, in the case of a payment of principal or any premium.

DTC, in turn, will notify the paying agent of your election in accordance with DTC’s procedures.

If complete instructions are received by the participant and forwarded by the participant to DTC, and by DTC to the paying agent, on or before the dates noted above, the paying agent, in accordance with DTC’s instructions, will make the payments to you or your participant by wire transfer of immediately available funds to an account maintained by the payee with a bank located in the country issuing the specified currency or in another jurisdiction acceptable to us and the paying agent.

If the foregoing steps are not properly completed, we expect DTC to inform the paying agent that payment is to be made in U.S. dollars. In that case, we or our agent will convert the payment to U.S. dollars in the manner described below under “—Conversion to U.S. Dollars.” We expect that we or our agent will then make the payment in U.S. dollars to DTC, and that DTC in turn will pass it along to its participants.

Indirect owners of a global debt security denominated in a currency other than U.S. dollars should consult their banks or brokers for information on how to request payment in the specified currency.

Payments on Non-Global Debt Securities. Except as described in the last paragraph under this heading, we will make payments on debt securities in non-global form in the applicable specified currency. We will make

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these payments by wire transfer of immediately available funds to any account that is maintained in the applicable specified currency at a bank designated by the holder and which is acceptable to us and the trustee. To designate an account for wire payment, the holder will be required to give the paying agent appropriate wire instructions at least five business days before the requested wire payment is due. In the case of any interest payment due on an interest payment date, the instructions will be required to be given by the person or entity who is the holder on the regular record date. In the case of any other payment, the payment will be made only after the debt security is surrendered to the paying agent. Any instructions, once properly given, will remain in effect unless and until new instructions are properly given in the manner described above.

If a holder fails to give instructions as described above, we will be required to notify the holder at the address in the trustee’s records and will make the payment within five business days after the holder provides appropriate instructions. Any late payment made in these circumstances will be treated under the applicable indenture as if made on the due date, and no interest will accrue on the late payment from the due date to the date paid.

Although a payment on a debt security in non-global form may be due in a specified currency other than U.S. dollars, we will make the payment in U.S. dollars if the holder asks us to do so. To request U.S. dollar payment, the holder will be required to provide appropriate written notice to the trustee at least five business days before the next due date for which payment in U.S. dollars is requested. In the case of any interest payment due on an interest payment date, the request will be required to be made by the person or entity who is the holder on the regular record date. Any request, once properly made, will remain in effect unless and until revoked by notice properly given in the manner described above.

Book-entry and other indirect owners of a debt security with a specified currency other than U.S. dollars should contact their banks or brokers for information about how to receive payments in the specified currency or in U.S. dollars.

Conversion to U.S. Dollars. When we are asked by a holder to make payments in U.S. dollars of an amount due in another currency, either on a global debt security or a non-global debt security as described above, the exchange rate agent described below will calculate the U.S. dollar amount the holder receives in the exchange rate agent’s discretion.

A holder that requests payment in U.S. dollars will bear all associated currency exchange costs, which will be deducted from the payment.

When the Specified Currency is Not Available. If we are obligated to make any payment in a specified currency other than U.S. dollars and the specified currency or any successor currency is not available to us due to circumstances beyond our control—such as the imposition of exchange controls or a disruption in the currency markets—we will be entitled to satisfy our obligation to make the payment in that specified currency by making the payment in U.S. dollars, on the basis of the exchange rate determined by the exchange rate agent described below, in its discretion.

The foregoing will apply to any debt security, whether in global or non-global form, and to any payment, including a payment at maturity. Any payment made under the circumstances and in a manner described above will not result in a default under any debt security or the applicable indenture.

Exchange Rate Agent. If we issue a debt security in a specified currency other than U.S. dollars, we will appoint a financial institution to act as the exchange rate agent and will name the institution initially appointed when the debt security is originally issued in the applicable prospectus supplement. We may change the exchange rate agent from time-to-time after the original issue date of the debt security without your consent and without notifying you of the change.

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All determinations made by the exchange rate agent will be in its sole discretion unless we state in the applicable prospectus supplement that any determination requires our approval. In the absence of manifest error, those determinations will be conclusive for all purposes and binding on you and us, without any liability on the part of the exchange rate agent.

Payment When Offices Are Closed

If any payment is due on a debt security on a day that is not a business day, we will make the payment on the next day that is a business day. Payments postponed to the next business day in this situation will be treated under the applicable indenture as if they were made on the original due date. Postponement of this kind will not result in a default under any debt security or the applicable indenture, and no interest will accrue on the postponed amount from the original due date to the next day that is a business day. The term business day has a special meaning, which we describe above under “—Payment and Record Dates for Interest.”

Paying Agent

We may appoint one or more financial institutions to act as our paying agents, at whose designated offices debt securities in non-global entry form may be surrendered for payment at their maturity. We call each of those offices a paying agent. We may add, replace or terminate paying agents from time-to-time. We may also choose to act as our own paying agent. Initially, we anticipate appointing the trustee, at its corporate trust office in New York City, as the paying agent. We must notify the trustee of changes in the paying agents.

Unclaimed Payments

Regardless of who acts as paying agent, all money paid by us to a paying agent that remains unclaimed at the end of two years after the amount is due to a holder will be repaid to us. After that two-year period, the holder may look only to us for payment and not to the trustee, any other paying agent or anyone else.

Notices

Notices to be given to holders of a global debt security will be given only to the depositary, in accordance with its applicable policies as in effect from time-to-time. Notices to be given to holders of debt securities not in global form will be sent by mail to the respective addresses of the holders as they appear in the trustee’s records. Neither the failure to give any notice to a particular holder, nor any defect in a notice given to a particular holder, will affect the sufficiency of any notice given to another holder.

Book-entry and other indirect owners should consult their banks or brokers for information on how they will receive notices.

DESCRIPTION OF PURCHASE CONTRACTS WE MAY OFFER

Please note that in this section entitled “Description of Purchase Contracts We May Offer,” references to “holders” mean those who own purchase contracts registered in their own names, on the books that we or our agent maintain for this purpose, and not those who own beneficial interests in purchase contracts registered in street name or in purchase contracts issued in book-entry form through one or more depositaries. Owners of beneficial interests in the purchase contracts should read the section below entitled “Legal Ownership and Book-Entry Issuance.”

This section outlines some of the provisions of the purchase contracts. This information may not be complete in all respects and is qualified entirely by reference to the purchase contract agreement with respect to the purchase contracts of any particular series. The specific terms of any series of purchase contracts will be

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described in the applicable prospectus supplement. If so described in a particular prospectus supplement, the specific terms of any series of purchase contracts may differ from the general description of terms presented below.

Unless otherwise specified in the applicable prospectus supplement, we may issue purchase contracts, including contracts obligating holders to purchase from us, and obligating us to sell to the holders, a number of shares of our common stock, preferred stock or depositary shares, debt securities or warrants, at a future date or dates. Alternatively, the purchase contracts may obligate use to purchase from holders, and obligate holders to sell to us, a specified or varying number of shares of common stock, preferred stock, depositary shares, debt securities, warrants or other security or property. The price per purchase contract security may be fixed at the time the purchase contracts are issued or may be determined by reference to a specific formula set forth in the purchase contracts. Under the purchase contracts, we may be required to make periodic payments to the holders of the units or vice versa. These payments may be unsecured or prefunded on some basis to be specified in the applicable prospectus supplement.

The purchase contracts may require holders to secure their obligations under the contracts in a specified manner and, in specified circumstances, we may deliver newly issued prepaid purchase contracts, or prepaid securities, when we transfer to a holder any collateral securing the holder’s obligations under the original purchase contract.

The purchase contracts may be issued separately or as part of units consisting of a purchase contract and one or more other securities, which may include our common stock, preferred stock, depositary shares, debt securities, warrants or debt obligations or government securities, and which may secure the holder’s obligations to purchase the purchase contract security under the purchase contract.

The applicable prospectus supplement relating to any purchase contracts we are offering will specify the material terms of the purchase contracts, whether they will be issued separately or as part of units, and any applicable pledge or depository arrangements.

DESCRIPTION OF UNITS WE MAY OFFER

Please note that in this section entitled “Description of Units We May Offer,” references to “holders” mean those who own units registered in their own names, on the books that we or our agent maintain for this purpose, and not those who own beneficial interests in units registered in street name or in units issued in book-entry form through one or more depositaries. Owners of beneficial interests in the units should read the section below entitled “Legal Ownership and Book-Entry Issuance.”

This section outlines some of the provisions of the units and the unit agreements. This information may not be complete in all respects and is qualified entirely by reference to the unit agreement with respect to the units of any particular series. The specific terms of any series of units will be described in the applicable prospectus supplement. If so described in a particular prospectus supplement, the specific terms of any series of units may differ from the general description of terms presented below.

As specified in the applicable prospectus supplement, we may issue units comprised of one or more of the other securities described in this prospectus or the securities of third parties in any combination. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security. The applicable prospectus supplement will describe:

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DESCRIPTION OF WARRANTS WE MAY OFFER

Please note that in this section entitled “Description of Warrants We May Offer,” references to “holders” mean those who own warrants or other rights registered in their own names, on the books that we or any applicable trustee or warrant or rights agent maintain for this purpose, and not those who own beneficial interests in warrants or rights registered in street name or in warrants or rights issued in book-entry form through one or more depositaries. Owners of warrants or rights or beneficial interests in warrants or rights should also read the section entitled “Legal Ownership and Book-Entry Issuance.”

This section outlines some of the provisions of each warrant agreement pursuant to which warrants may be issued, the warrants or rights, and any warrant or rights certificates. This information may not be complete in all respects and is qualified entirely by reference to any warrant agreement with respect to the warrants or rights of any particular series. The specific terms of any series of warrants or rights will be described in the applicable prospectus supplement. If so described in the prospectus supplement, the terms of that series of warrants or rights may differ from the general description of terms presented below.

General

We may issue warrants for the purchase of common stock, preferred stock, depositary shares, debt securities or units, or any combination thereof, in one or more series. We may issue warrants independently or together with common stock, preferred stock, depositary shares, debt securities and/or units, and the warrants may be attached to or separate from these securities.

We will evidence each series of warrants by warrant certificates that we may issue under a separate agreement. We may enter into a warrant agreement with a warrant agent. Each warrant agent may be a bank that we select which has its principal office in the United States. We may also choose to act as our own warrant agent. We will indicate the name and address of any such warrant agent in the applicable prospectus supplement relating to a particular series of warrants.

We will describe in the applicable prospectus supplement the terms of any particular series of warrants, including:

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Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including the right to receive dividends, if any, or payments upon our liquidation, dissolution or winding up or to exercise voting rights, if any.

Upon receipt of the required payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement, we will issue and deliver the securities purchasable upon such exercise. If fewer than all of the warrants represented by the warrant certificate are exercised, then we will issue a new warrant certificate for the remaining amount of warrants.

LEGAL OWNERSHIP AND BOOK-ENTRY ISSUANCE

In this section, we describe special considerations that will apply to registered securities issued in global—i.e., book-entry—form. First we describe the difference between legal ownership and indirect ownership of registered securities. Then we describe special provisions that apply to global securities.

Who Is the Legal Owner of a Registered Security?

Each share of common stock, share of preferred stock, depositary share, debt security, purchase contract, unit and warrant in registered form will be represented either by a certificate issued in definitive form to a particular investor or by one or more global securities representing the entire issuance of securities. We refer to those who have securities registered in their own names, on the books that we or the trustee, warrant agent or other agent maintain for this purpose, as the “holders” of those securities. These persons will be the legal holders of the securities. We refer to those who, indirectly through others, own beneficial interests in securities that are not registered in their own names as indirect owners of those securities. As we discuss below, indirect owners will not be legal holders, and investors in securities issued in book-entry form or in street name will be indirect owners.

Book-Entry Owners. We will issue each security in book-entry form only, unless we specify otherwise in the applicable prospectus supplement. This means securities will be represented by one or more global securities registered in the name of a financial institution that holds them as depositary on behalf of other financial institutions that participate in the depositary’s book-entry system. These participating institutions, in turn, hold beneficial interests in the securities on behalf of themselves or their customers.

Under each indenture, only the person in whose name a security is registered will be recognized as the holder of that security. Consequently, for securities issued in global form, we will recognize only the depositary

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as the holder of the securities and we will make all payments on the securities, including deliveries of any property other than cash, to the depositary. The depositary passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depositary and its participants do so under agreements they have made with one another or with their customers; they are not obligated to do so under the terms of the securities.

As a result, investors will not own securities directly. Instead, they will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depositary’s book-entry system or holds an interest through a participant. As long as the securities are issued in global form, investors will be indirect owners, and not holders, of the securities.

Street Name Owners. In the future we may terminate a global security or issue securities initially in non-global form. In these cases, investors may choose to hold their securities in their own names or in street name. Securities held by an investor in street name would be registered in the name of a bank, broker or other financial institution that the investor chooses, and the investor would hold only a beneficial interest in those securities through an account he or she maintains at that institution.

For securities held in street name, we will recognize only the intermediary banks, brokers and other financial institutions in whose names the securities are registered as the holders of those securities and we will make all payments on those securities, including deliveries of any property other than cash, to them. These institutions pass along the payments they receive to their customers who are the beneficial owners but only because they agree to do so in their customer agreements or because they are legally required to do so. Investors who hold securities in street name will be indirect owners, not holders, of those securities.

Legal Holders. Our obligations, as well as the obligations of the trustee under any indenture and the obligations, if any, of any warrant agents and unit agents and any other third parties employed by us, the trustee or any of those agents, run only to the holders of the securities. We have no obligations to investors who hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether an investor chooses to be an indirect owner of a security or has no choice because we are issuing the securities only in global form.

For example, once we make a payment or give a notice to the holder, we have no further responsibility for that payment or notice even if that holder is required, under agreements with depositary participants or customers or by law, to pass it along to the indirect owners but does not do so. Similarly, if we want to obtain the approval of the holders for any purpose—e.g., to amend the indenture for a series of debt securities or warrants or the warrant agreement for a series of warrants or to relieve us of the consequences of a default or of our obligation to comply with a particular provision of an indenture—we would seek the approval only from the holders, and not the indirect owners, of the relevant securities. Whether and how the holders contact the indirect owners is up to the holders.

When we refer to “you” in this prospectus, we mean those who invest in the securities being offered by this prospectus, whether they are the holders or only indirect owners of those securities. When we refer to “your securities” in this prospectus, we mean the securities in which you will hold a direct or indirect interest.

Special Considerations for Indirect Owners. If you hold securities through a bank, broker or other financial institution, either in book-entry form or in street name, you should check with your own institution to find out:

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What Is a Global Security? We will issue each security in book-entry form only, unless we specify otherwise in the applicable prospectus supplement. Each security issued in book-entry form will be represented by a global security that we deposit with and register in the name of one or more financial institutions or clearing systems, or their nominees, which we select. A financial institution or clearing system that we select for any security for this purpose is called the “depositary” for that security. A security will usually have only one depositary but it may have more depositaries.

Each series of securities will have one or more of the following as the depositaries:

The depositaries named above may also be participants in one another’s systems. Thus, for example, if DTC is the depositary for a global security, investors may hold beneficial interests in that security through Euroclear or Clearstream, as DTC participants. The depositary or depositaries for your securities will be named in the prospectus supplement; if none is named, the depositary will be DTC.

A global security may represent one or any other number of individual securities. Generally, all securities represented by the same global security will have the same terms. We may, however, issue a global security that represents multiple securities of the same kind, such as debt securities, that have different terms and are issued at different times. We call this kind of global security a master global security. The applicable prospectus supplement will not indicate whether your securities are represented by a master global security.

A global security may not be transferred to or registered in the name of anyone other than the depositary or its nominee, unless special termination situations arise. We describe those situations below under “—Holder’s Option to Obtain a Non-Global Security; Special Situations When a Global Security Will Be Terminated.” As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and holder of all securities represented by a global security, and investors will be permitted to own only indirect interests in a global security. Indirect interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depositary or with another institution that does. Thus, an investor whose security is represented by a global security will not be a holder of the security, but only an indirect owner of an interest in the global security.

If the applicable prospectus supplement for a particular security indicates that the security will be issued in global form only, then the security will be represented by a global security at all times unless and until the global security is terminated. We describe the situations in which this can occur below under “—Holder’s Option to Obtain a Non-Global Security; Special Situations When a Global Security Will Be Terminated.” If termination occurs, we may issue the securities through another book-entry clearing system or decide that the securities may no longer be held through any book-entry clearing system.

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Special Considerations for Global Securities

As an indirect owner, an investor’s rights relating to a global security will be governed by the account rules of the depositary and those of the investor’s financial institution or other intermediary through which it holds its interest (e.g., Euroclear or Clearstream, if DTC is the depositary), as well as general laws relating to securities transfers. We do not recognize this type of investor or any intermediary as a holder of securities and instead deal only with the depositary that holds the global security.

If securities are issued only in the form of a global security, an investor should be aware of the following:

Holder’s Option to Obtain a Non-Global Security; Special Situations When a Global Security Will Be Terminated

If we issue any series of securities in book-entry form but we choose to give the beneficial owners of that series the right to obtain non-global securities, any beneficial owner entitled to obtain non-global securities may do so by following the applicable procedures of the depositary, any transfer agent or registrar for that series and that owner’s bank, broker or other financial institution through which that owner holds its beneficial interest in the securities. For example, in the case of a global security representing preferred stock or depositary shares, a beneficial owner will be entitled to obtain a non-global security representing its interest by making a written

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request to the transfer agent or other agent designated by us. If you are entitled to request a non-global certificate and wish to do so, you will need to allow sufficient lead time to enable us or our agent to prepare the requested certificate.

In addition, in a few special situations described below, a global security will be terminated and interests in it will be exchanged for certificates in non-global form representing the securities it represented. After that exchange, the choice of whether to hold the securities directly or in street name will be up to the investor. Investors must consult their own banks or brokers to find out how to have their interests in a global security transferred on termination to their own names, so that they will be holders. We have described the rights of holders and street name investors above under “—Who Is the Legal Owner of a Registered Security?”

The special situations for termination of a global security are as follows:

If a global security is terminated, only the depositary, and not we, the trustee for any debt securities or the warrant agent for any warrants or the unit agent for any units, is responsible for deciding the names of the institutions in whose names the securities represented by the global security will be registered and, therefore, who will be the holders of those securities.

Considerations Relating to Euroclear and Clearstream

Euroclear and Clearstream are securities clearance systems in Europe. Both systems clear and settle securities transactions between their participants through electronic, book-entry delivery of securities against payment.

Euroclear and Clearstream may be depositaries for a global security. In addition, if DTC is the depositary for a global security, Euroclear and Clearstream may hold interests in the global security as participants in DTC.

As long as any global security is held by Euroclear or Clearstream, as depositary, you may hold an interest in the global security only through an organization that participates, directly or indirectly, in Euroclear or Clearstream. If Euroclear or Clearstream is the depositary for a global security and there is no depositary in the United States, you will not be able to hold interests in that global security through any securities clearance system in the United States.

Payments, deliveries, transfers, exchanges, notices and other matters relating to the securities made through Euroclear or Clearstream must comply with the rules and procedures of those systems. Those systems could change their rules and procedures at any time. We do not have control over those systems or their participants, and we do not take responsibility for their activities. Transactions between participants in Euroclear or Clearstream, on one hand, and participants in DTC, on the other hand, when DTC is the depositary, would also be subject to DTC’s rules and procedures.

Special Timing Considerations for Transactions in Euroclear and Clearstream

Investors will be able to make and receive through Euroclear and Clearstream payments, deliveries, transfers, exchanges, notices and other transactions involving any securities held through those clearing systems only on days when those systems are open for business. Those clearing systems may not be open for business on days when banks, brokers and other institutions are open for business in the United States.

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In addition, because of time-zone differences, U.S. investors who hold their interests in the securities through these clearing systems and wish to transfer their interests, or to receive or make a payment or delivery or exercise any other right with respect to their interests, on a particular day may find that the transaction will not be effected until the next business day in Luxembourg or Brussels, as applicable. Thus, investors who wish to exercise rights that expire on a particular day may need to act before the expiration date. In addition, investors who hold their interests through both DTC and Euroclear or Clearstream may need to make special arrangements to finance any purchases or sales of their interests between the U.S. and European clearing systems, and those transactions may settle later than would be the case for transactions within one clearing system.

PLAN OF DISTRIBUTION

We may offer and sell the securities from time to time as follows:

In addition, the securities may be issued as a dividend or distribution or in a subscription rights offering to existing holders of securities. In some cases, we may also repurchase securities and reoffer them to the public by one or more of the methods described above.

The securities we distribute by any of these methods may be sold to the public, in one or more transactions, either:

We may solicit offers to purchase securities directly from the public from time to time. We may also designate agents from time to time to solicit offers to purchase securities from the public on our behalf. If required, the prospectus supplement relating to any particular offering of securities will name any agents designated to solicit offers, and will include information about any commissions we may pay the agents, in that offering. Agents may be deemed to be “underwriters” as that term is defined in the Securities Act of 1933, as amended (the “Securities Act”).

From time to time, we may sell securities to one or more dealers as principals. The dealers, who may be deemed to be “underwriters” as that term is defined in the Securities Act, may then resell those securities to the public.

We may sell securities from time to time to one or more underwriters, who would purchase the securities as principal for resale to the public, either on a firm-commitment or best-efforts basis. If we sell securities to underwriters, we will execute an underwriting agreement with them at the time of sale and will name them in the applicable prospectus supplement. In connection with those sales, underwriters may be deemed to have received compensation from us in the form of underwriting discounts or commissions and may also receive commissions from purchasers of the securities for whom they may act as agents. Underwriters may resell the securities to or

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through dealers, and those dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters and/or commissions from purchasers for whom they may act as agents. The applicable prospectus supplement will include any required information about any underwriting compensation we pay to underwriters, and any discounts, concessions or commissions underwriters allow to participating dealers, in connection with an offering of securities.

If we offer securities in a subscription rights offering to our existing securityholders, we may enter into a standby underwriting agreement with dealers, acting as standby underwriters. We may pay the standby underwriters a commitment fee for the securities they commit to purchase on a standby basis. Additionally, before the expiration date for the subscription rights, the standby underwriters may offer the securities, including securities they may acquire through the purchase and exercise of subscription rights, on a when-issued basis at prices set from time to time by them. After the expiration date, the standby underwriters may offer the securities, whether acquired under the standby underwriting agreement, on exercise of subscription rights or by purchase in the market, to the public at prices to be determined by them. Thus, standby underwriters may realize profits or losses independent of the underwriting discounts or commissions we may pay them. If we do not enter into a standby underwriting arrangement, we may retain a dealer-manager to manage a subscription rights offering for us. Any dealer-manager we retain may acquire securities by purchasing and exercising the subscription rights and resell the securities to the public at prices it determines. As a result, a dealer-manager may realize profits or losses independent of any dealer-manager fee paid by us.

We may authorize underwriters, dealers and agents to solicit from third parties offers to purchase securities under contracts providing for payment and delivery on future dates. The third parties with whom we may enter into contracts of this kind may include banks, insurance companies, pension funds, investment companies, educational and charitable institutions, and others. The applicable prospectus supplement will describe the material terms of these contracts, including any conditions to the purchasers’ obligations and will include any required information about any commissions we may pay for soliciting these contracts.

We may enter into derivative transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with those derivatives, the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, the third party may use securities pledged by us or borrowed from us or others to settle those sales or to close out any related open borrowings of stock, and may use securities received from us in settlement of those derivatives to close out any related open borrowings of stock. The third party in such sale transactions will be an underwriter and will be identified in the applicable prospectus supplement (or a post-effective amendment).

Underwriters, dealers, agents and other persons may be entitled, under agreements that they may enter into with us, to indemnification by us against civil liabilities, including liabilities under the Securities Act.

Underwriters may engage in stabilizing and syndicate covering transactions in accordance with Rule 104 of Regulation M. Rule 104 permits stabilizing bids to purchase the securities being offered as long as the stabilizing bids do not exceed a specified maximum. Underwriters may over-allot the offered securities in connection with the offering, thus creating a short position in their account. Syndicate covering transactions involve purchases of the offered securities by underwriters in the open market after the distribution has been completed in order to cover syndicate short positions. Stabilizing and syndicate covering transactions may cause the price of the offered securities to be higher than it would otherwise be in the absence of these transactions. These transactions, if commenced, may be discontinued at any time.

The underwriters, dealers and agents, as well as their associates, may be customers of or lenders to, and may engage in transactions with and perform services for, Columbia and its subsidiaries in the ordinary course of business.

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Under Rule 15c6-1 of the Exchange Act, trades in the secondary market generally are required to settle in two business days, unless the parties to any such trade expressly agree otherwise. The applicable prospectus supplement may provide that the original issue date for your securities may be more or less than two scheduled business days after the trade date for your securities.

CERTAIN ERISA CONSIDERATIONS

A fiduciary of a (i) pension, profit-sharing or other employee benefit plan subject to the Employee Retirement Income Security Act of 1974, as amended (“ERISA”), or (ii) an entity whose underlying assets include “plan assets” by reason of such plan’s investment in the entity (collectively, “Plans”), should consider the fiduciary standards of ERISA in the context of the Plan’s particular circumstances before authorizing an investment in the securities. Among other factors, the fiduciary should consider whether the investment would satisfy the prudence and diversification requirements of ERISA and would be consistent with the documents and instruments governing the Plan, and whether the investment would involve a prohibited transaction under ERISA or the U.S. Internal Revenue Code of 1986, as amended (the “Code”).

Section 406 of ERISA and Section 4975 of the Code prohibit Plans, as well as individual retirement accounts (“IRAs”), Keogh plans and other plans that are subject to Section 4975 of the Code (also “Plans”), from engaging in certain transactions involving “plan assets” with persons who are “parties in interest” under ERISA or “disqualified persons” under the Code with respect to the Plan. A violation of these prohibited transaction rules may result in excise tax or other liabilities under ERISA or the Code for those persons, unless exemptive relief is available under an applicable statutory, regulatory or administrative exemption. Employee benefit plans that are governmental plans (as defined in Section 3(32) of ERISA), certain church plans (as defined in Section 3(33) of ERISA) and non-U.S. plans (as described in Section 4(b)(4) of ERISA) (“Non-ERISA Arrangements”) are not subject to the requirements of Section 406 of ERISA or Section 4975 of the Code but may be subject to similar provisions under applicable federal, state, local, non-U.S. or other laws (“ERISA Similar Laws”).

The acquisition and holding of the securities by a Plan with respect to which Columbia or any of its respective affiliates is or becomes a party in interest or disqualified person may result in a prohibited transaction under ERISA or Section 4975 of the Code, unless the securities are acquired and held pursuant to an applicable exemption. The U.S. Department of Labor has issued various prohibited transaction class exemptions, or “PTCEs,” that may provide exemptive relief if required for direct or indirect prohibited transactions that may arise from the purchase or holding of the securities. These exemptions include PTCE 84-14 (for certain transactions determined by independent qualified professional asset managers), PTCE 90-1 (for certain transactions involving insurance company pooled separate accounts), PTCE 91-38 (for certain transactions involving bank collective investment funds), PTCE 95-60 (for transactions involving certain insurance company general accounts), and PTCE 96-23 (for transactions managed by in-house asset managers). There can be no assurance that all of the conditions of any such exemptions will be satisfied.

Unless otherwise provided in connection with a particular offering of securities by Columbia, any purchaser, holder or subsequent transferee of the securities or any interest therein will be deemed to have represented by its purchase and holding of the securities or any interest therein that it either (i) is not a Plan or a Non-ERISA Arrangement and is not purchasing the securities on behalf of or with the assets of any Plan or Non-ERISA Arrangement or (ii) the purchase and holding of the securities will not constitute a non-exempt prohibited transaction under ERISA or the Code or a similar violation under any applicable ERISA Similar Laws.

Due to the complexity of these rules and the penalties that may be imposed upon persons involved in non-exempt prohibited transactions, it is important that fiduciaries or other persons considering investing in the securities on behalf of or with the assets of any Plan or Non-ERISA Arrangement consult with their counsel regarding the availability of exemptive relief under any of the PTCEs listed above, the service provider

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exemption or the potential consequences of any purchase or holding under ERISA Similar Laws, as applicable. Purchasers of the securities have exclusive responsibility for ensuring that their purchase and holding of the securities do not violate the fiduciary or prohibited transaction rules of ERISA or the Code or any similar provisions of ERISA Similar Laws. The sale of any securities to a Plan or Non-ERISA Arrangement is in no respect a recommendation to purchase the securities or a representation by Columbia or any of its affiliates or representatives that such an investment meets all relevant legal requirements with respect to investments by any such Plans or Non-ERISA Arrangements generally or any particular Plan or Non-ERISA Arrangement or that such investment is appropriate for such Plans or Non-ERISA Arrangements generally or any particular Plan or Non-ERISA Arrangement.

ANY POTENTIAL INVESTOR CONSIDERING AN INVESTMENT IN THE SECURITIES THAT IS, OR IS ACTING ON BEHALF OF, A PLAN OR NON-ERISA ARRANGEMENT IS STRONGLY URGED TO CONSULT ITS OWN LEGAL AND TAX ADVISORS REGARDING THE CONSEQUENCES OF SUCH AN INVESTMENT UNDER ERISA, THE CODE AND ANY OTHER ERISA SIMILAR LAW AND ITS ABILITY TO MAKE THE REPRESENTATIONS DESCRIBED ABOVE.

VALIDITY OF THE SECURITIES

Unless otherwise specified in the applicable prospectus supplement, the validity of the common stock, preferred stock, and common stock or preferred stock issuable upon the exercise, conversion or exchange of other securities, will be passed upon for us by Ms. Kumi Y. Baruffi, Executive Vice President and General Counsel of Columbia and the validity of the debt securities, depositary shares, warrant agreements, purchase contracts, units and any debt securities or depositary shares issuable upon the conversion of other securities, will be passed upon for us by Sullivan & Cromwell LLP, Los Angeles, California. Certain legal matters will be passed upon for any agents, dealers or underwriters by counsel named in the applicable prospectus supplement. As of March 31, 2018, Ms. Baruffi owned less than 1% of the outstanding shares of Columbia. Sullivan & Cromwell LLP from time to time performs legal services for Columbia.

EXPERTS

The consolidated financial statements incorporated in this prospectus by reference from Columbia’s Report on Form 10-K and the effectiveness of Columbia’s internal control over financial reporting, have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their reports, which are incorporated herein by reference. Such consolidated financial statements have been so incorporated in reliance upon the reports of such firm given upon their authority as experts in accounting and auditing.

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COLUMBIA BANKING SYSTEM, INC.

COMMON STOCK

PREFERRED STOCK

DEPOSITARY SHARES

DEBT SECURITIES

PURCHASE CONTRACTS

UNITS

WARRANTS

PROSPECTUS

August 3, 2018

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

The expenses relating to the registration of the securities will be borne by the registrant. Such expenses, other than underwriting discounts and commissions and the Securities and Exchange Commission (the “SEC”) registration fee, are estimated to be as follows:

Sections 23B.08.500 through 23B.08.603 of the Washington Business Corporation Act (the “WBCA”) contain specific provisions relating to indemnification of directors and officers of Washington corporations. In general, the statute provides that (a) a corporation must indemnify a director or officer who is wholly successful in his defense of a proceeding to which he is a party because of his status as such, unless limited by the articles of incorporation, and (b) a corporation may indemnify a director or officer if he is not wholly successful in such defense, if it is determined as provided in the statute that the director meets a certain standard of conduct, provided that a corporation may not indemnify a director in connection with a proceeding by or in the right of the corporation in which the director is adjudged liable to the corporation, or in connection with a proceeding charging improper personal benefit to the director, in which the director is adjudged liable on the basis that the personal benefit was improperly received by the director. The statute also permits a director or officer of a corporation who is a party to a proceeding to apply to the courts for indemnification or advance of expenses, unless the articles of incorporation provide otherwise, and the court may order indemnification or advancement of expenses under certain circumstances set forth in the statute. The statute further provides that a corporation may, if authorized by its articles of incorporation or bylaws or by resolution adopted or ratified by the shareholders, provide indemnification in addition to that provided by statute, subject to certain conditions set forth in the statute.

The Amended and Restated Articles of Incorporation of Columbia, as amended (the “Articles of Incorporation”), provide, among other things, for the indemnification of directors, and authorize the board of directors to pay reasonable expenses incurred by, or to satisfy a judgment or fine against, a current of former director in connection with any personal legal liability incurred by the individual while acting for Columbia within the scope of his employment, and which was not the result of conduct finally found to be “egregious” conduct. “Egregious” conduct is defined in the Articles of Incorporation to include intentional misconduct, a knowing violation of law, or participation in any transaction from which the person will personally receive a benefit in money, property or services to which that person is not legally entitled. The Articles of Incorporation also include a provision that limits the liability of directors of Columbia from any personal liability to Columbia or its shareholders for monetary damages for conduct not found to have been egregious.

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Columbia has entered into Indemnification Agreements with each of its directors. The Indemnification Agreements codify procedural mechanisms pursuant to which directors may enforce the indemnification rights that such directors are granted under Columbia’s Articles of Incorporation and the WBCA.

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The undersigned registrant hereby undertakes:

1. To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i) To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20 percent change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement; and

(iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, that paragraphs (i), (ii) and (iii) above do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the registrant pursuant to section 13 or section 15(d) of the Securities and Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

2. That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

3. To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

4. That, for the purpose of determining liability under the Securities Act of 1933 to any purchaser:

(i) Each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

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(ii) Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5), or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii), or (x) for the purpose of providing the information required by section 10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date.

5. That, for the purpose of determining liability of the registrant under the Securities Act of 1933 to any purchaser in the initial distribution of the securities:

The undersigned registrant undertakes that in a primary offering of securities of the undersigned registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

(i) Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

(ii) Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

(iii) The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

(iv) Any other communication that is an offer in the offering made by the undersigned registrant to the purchaser.

6. That, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant’s annual report pursuant to Sections 13(a) or 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to section 15(d) of the Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

7. Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act of 1933 and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by

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it is against public policy as expressed in the Securities Act of 1933 and will be governed by the final adjudication of such issue.

8. To file an application for the purpose of determining the eligibility of the trustee to act under subsection (a) of Section 310 of the Trust Indenture Act in accordance with the rules and regulations prescribed by the Securities and Exchange Commission under Section 305(b)(2) of the Act.

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Tacoma, State of Washington on August 3, 2018.

Each person whose individual signature appears below hereby authorizes and appoints Hadley S. Robbins, Client E. Stein and Gregory A. Sigrist, and each of them, with full power of substitution and full power to act without the other, as his true and lawful attorney-in-fact and agent to act in his name, place and stead and to execute in the name and on behalf of each person, individually and in each capacity stated below, and to file any and all amendments, including any and all amendments to this registration statement, all post-effective amendments and any subsequent registration statement for the same offering which may be filed under Rule 462 under the Securities Act of 1933, as amended, and to file the same with exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission.

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed by the following persons in the capacities and on the dates indicated.

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