SUMMARY

This summary highlights some of the information in this joint proxy statement/prospectus. It may not contain all of the information that is important to you. To understand the Atlas Mergers fully and for a more complete description of the terms of the Atlas Mergers, you should read carefully this document, the documents incorporated by reference, and the Annexes to this document, including the full text of the Atlas Merger Agreements included as Annex A and Annex B. Please also read “Where You Can Find More Information.”

The Parties

Targa Resources Corp.

Targa Resources Corp., or TRC, is a publicly traded Delaware corporation formed in October 2005. TRC does not directly own any operating assets; its main source of future revenue therefore is from general and limited partner interests, including incentive distribution rights (“IDRs”), in TRP. TRC’s shares of common stock are listed on the NYSE under the symbol “TRGP.”

TRC’s principal executive offices are located at 1000 Louisiana Street, Suite 4300, Houston, Texas 77002 and its telephone number is 713-584-1000.

Targa Resources Partners LP

Targa Resources Partners LP, or TRP, is a publicly traded Delaware limited partnership formed in October 2006 by its parent, TRC, to own, operate, acquire and develop a diversified portfolio of complementary midstream energy assets. TRP’s common units are listed on the NYSE under the symbol “NGLS.” TRP is a leading provider of midstream natural gas and natural gas liquids (“NGL”) services in the United States, with a growing presence in crude oil gathering and petroleum terminaling.

TRP is engaged in the business of:

TRP’s principal executive offices are located at 1000 Louisiana Street, Suite 4300, Houston, Texas 77002 and its telephone number is 713-584-1000.

Atlas Energy, L.P.

Atlas Energy, L.P., or ATLS, is a publicly traded Delaware master limited partnership whose common units are listed on the NYSE under the symbol “ATLS.” Its assets currently consist principally of its ownership interests in the following:

ATLS’s principal executive offices are located at Park Place Corporate Center One, 1000 Commerce Drive, 4th Floor, Pittsburgh, Pennsylvania 15275-1011, and its telephone number is (877) 950-7473.

Atlas Pipeline Partners, L.P.

Atlas Pipeline Partners, L.P, or APL, is a publicly traded Delaware limited partnership formed in 1999 whose common units are listed on the NYSE under the symbol “APL.” APL is a leading provider of natural gas gathering, processing and treating services primarily in the Anadarko, Arkoma and Permian Basins located in the southwestern and mid-continent regions of the United States and in the Eagle Ford Shale play in south Texas; a provider of natural gas gathering services in the Appalachian Basin in the northeastern region of the United States and a provider of NGL transportation services in the southwestern region of the United States.

APL’s general partner, Atlas Pipeline Partners GP, LLC, manages its operations and activities through its ownership of APL’s general partner interest. Atlas Pipeline GP is a wholly owned subsidiary of ATLS, which owned 5.5% of the limited partner interests in APL at October 31, 2014, as well as a 2.0% general partner interest.

APL’s principal executive offices are located at Park Place Corporate Center One, 1000 Commerce Drive, 4th Floor, Pittsburgh, Pennsylvania 15275-1011, and its telephone number is (877) 950-7473.

Relationships Between the Parties

Prior to May 2014, APL indirectly held an aggregate 20% interest in West Texas LPG Pipeline Limited Partnership (“WTLPG”), which owns a common-carrier pipeline system that transports NGLs from New Mexico and Texas to Mont Belvieu, Texas for fractionation. During 2011, 2012 and 2013, certain subsidiaries of TRP paid WTLPG approximately $25.4 million, $20.8 million and $22.9 million, respectively, for the WTLPG tariffs, net payments for system losses/gains and reimbursements for connections and other construction costs. For the nine months ended September 30, 2013 and 2014, certain subsidiaries of TRP paid WTLPG approximately $17.4 and $20.0 million, respectively, for the WTLPG tariffs, net payments for system losses/gains and reimbursements for connections and other construction costs.

During 2013, certain subsidiaries of TRP paid Atlas Barnett LLC and Atlas Pipeline Mid-Continent LLC, subsidiaries of APL, approximately $4.4 million pursuant to certain gas purchase agreements. For the nine months ended September 30, 2013 and 2014, certain subsidiaries of TRP paid Atlas Barnett LLC and Atlas Pipeline Mid-Continent LLC approximately $2.1 million and $8.4 million, respectively, pursuant to certain gas purchase agreements.

The Transactions

On October 13, 2014, TRC and ATLS entered into an Agreement and Plan of Merger with GP Merger Sub and ATLS GP, which we refer to as the ATLS Merger Agreement. The ATLS Merger Agreement provides that, upon the terms and subject to the conditions set forth therein, GP Merger Sub will merge with and into ATLS, with ATLS surviving the merger as a subsidiary of TRGP, which we refer to as the ATLS Merger.

Concurrently with the execution of the ATLS Merger Agreement, on October 13, 2014, TRP and APL entered into an Agreement and Plan of Merger with TRC, TRP GP, MLP Merger Sub, ATLS and APL GP, which we refer to as the APL Merger Agreement. The APL Merger Agreement provides that, upon the terms and subject to the conditions set forth therein, immediately following the ATLS Merger, MLP Merger Sub will merge with and into APL, with APL surviving the merger as a subsidiary of NGLS, which we refer to as the APL Merger.

Subject to the terms and conditions set forth in the ATLS Merger Agreement, ATLS has agreed that it will, pursuant to the Separation Agreement, (1) transfer its assets and liabilities other than those related to its “Atlas Pipeline Partners” segment to Atlas Energy Group, LLC, which we refer to as New Atlas, and (2) immediately prior to the ATLS Merger, effect a pro rata distribution to the ATLS unitholders of New Atlas common units representing a 100% interest in New Atlas, which we refer to as the Spin-Off.

Each of the Transactions is cross-conditioned (subject to permitted waiver) on either the consummation of each of the other Transactions or the parties’ agreement that such other Transactions will occur substantially concurrently with the other Transactions.

The ATLS Merger Consideration

The ATLS Merger Agreement provides that, at the ATLS Effective Time, each ATLS common unit issued and outstanding immediately prior to the ATLS Effective Time will be converted into the right to receive (i) 0.1809 of a share of TRC common stock, which we refer to as the ATLS Stock Consideration, and (ii) cash in the amount of $9.12, which we refer to as the ATLS Cash Consideration and, together with the ATLS Stock Consideration, the ATLS Merger Consideration. Any ATLS common units owned immediately prior to the ATLS Effective Time by ATLS or its wholly owned subsidiaries or by TRC or its wholly owned subsidiaries will be cancelled without any conversion or payment of consideration in respect thereof.

The APL Merger Consideration

The APL Merger Agreement provides that, at the APL Effective Time, each APL unit issued and outstanding immediately prior to the APL Effective Time will be converted into the right to receive (i) 0.5846 of a TRP common unit, which we refer to as the APL Unit Consideration, and (ii) cash in the amount of $1.26, which we refer to as the APL Cash Consideration and, together with the APL Unit Consideration, the APL Merger Consideration. Any APL common units owned immediately prior to the APL Effective Time by APL or its wholly owned subsidiaries or by TRP or its wholly owned subsidiaries will be cancelled without any conversion or payment of consideration in respect thereof.

Treatment of ATLS Equity Awards

Spin-Off Adjustment to ATLS Equity Awards

In connection with the Spin-Off, each option to purchase ATLS common units will be converted into an adjusted ATLS option and a New Atlas option. We refer to each of the ATLS options as adjusted in connection

with the Spin-Off as an “adjusted ATLS option.” The exercise price and number of units subject to each option will be adjusted in order to preserve the aggregate intrinsic value of the original ATLS option as measured immediately before and immediately after the Spin-Off, subject to rounding.

Holders of ATLS phantom unit awards will retain those awards and also will receive a New Atlas phantom unit award covering a number of New Atlas common units that reflects the distribution to ATLS unitholders, determined by applying the distribution ratio in the Spin-Off to the ATLS phantom unit awards as though they were actual ATLS common units. We refer to each of ATLS phantom units as an “original ATLS phantom unit.”

Treatment of New Atlas Equity Awards

Immediately following the Spin-Off, all New Atlas options and phantom unit awards will become fully vested and will be cancelled and settled for the implied value of a New Atlas common unit less, in the case of New Atlas options, the applicable exercise price. All New Atlas options and phantom unit awards will be settled in cash, subject to a specified aggregate cap on the amount of cash that may be distributed in respect of all New Atlas equity awards. If the cap is exceeded, then any amounts payable to holders of New Atlas equity awards in excess of the cap will be settled in New Atlas common units. If the cap is not exceeded, then any excess available cash will be distributed to the holders of New Atlas phantom unit awards on a pro rata basis. The computation of the cap is discussed in more detail in the section entitled “The Transactions—Interests of Certain Persons in the Transaction—Severance Payments.”

ATLS Equity Awards Held by New Atlas Allocated Employees

Adjusted ATLS Options. Each adjusted ATLS option, whether vested or unvested, that is held by an employee of New Atlas following the Spin-Off (whom we refer to collectively as “New Atlas allocated employees”), a non-employee director of ATLS or APL, or a former employee, and that is outstanding immediately prior to the ATLS Effective Time, will, as of the ATLS Effective Time, become fully vested and be cancelled and converted into the right to receive the ATLS Merger Consideration in respect of each ATLS common unit underlying the adjusted ATLS option, net of the applicable exercise price. Any adjusted ATLS option that has an exercise price that is greater than or equal to the cash value of the ATLS Merger Consideration will be cancelled for no consideration.

Original ATLS Phantom Unit Awards. Each original ATLS phantom unit that is held by a New Atlas allocated employee, a non-employee director of ATLS or APL, or a former employee, and that is outstanding immediately prior to the ATLS Effective Time, will, as of the ATLS Effective Time, become fully vested and be cancelled and converted into the right to receive the ATLS Merger Consideration in respect of each ATLS common unit underlying the original ATLS phantom unit award.

ATLS Equity Awards Held by ATLS Employees

Adjusted ATLS Options. Each vested adjusted ATLS option that is held by an employee of ATLS following the Spin-Off (whom we refer to as “ATLS allocated employees”), and that is outstanding immediately prior to the ATLS Effective Time, will, as of the ATLS Effective Time, be cancelled and converted into the right to receive the ATLS Merger Consideration in respect of each ATLS common unit underlying the adjusted ATLS option, net of the applicable exercise price.

Each unvested adjusted ATLS option that is held by an ATLS allocated employee and outstanding immediately prior to the ATLS Effective Time, will, as of the ATLS Effective Time, be cancelled and converted into the right to receive (net of the applicable exercise price): (1) the ATLS Cash Consideration in respect of each ATLS common unit underlying the adjusted ATLS option and (2) a TRC restricted stock award with respect to a

number of shares of TRC common stock (rounded down to the nearest whole share) equal to the product of (a) the number of ATLS common units underlying the adjusted ATLS option, multiplied by (b) the ATLS Stock Consideration. Each TRC restricted stock award will settle in TRC common stock upon vesting.

Any adjusted ATLS option that has an exercise price that is greater than or equal to the cash value of the ATLS Merger Consideration will be cancelled for no consideration.

Original ATLS Phantom Unit Awards. Each original ATLS phantom unit award that is held by an ATLS allocated employee and outstanding immediately prior to the ATLS Effective Time, will, as of the ATLS Effective Time, be cancelled and converted into the right to receive: (1) the ATLS Cash Consideration in respect of each ATLS common unit underlying the original ATLS phantom unit award and (2) a TRC restricted stock award with respect to a number of shares of TRC common stock (rounded to the nearest whole share) equal to the product of (a) the number of ATLS common units underlying the original ATLS phantom unit award, multiplied by (b) the ATLS Stock Consideration. Each TRC restricted stock award will settle in TRC common stock upon vesting.

Treatment of APL Equity Awards

APL Phantom Unit Awards Held by New Atlas Allocated Employees

Each APL phantom unit award that is outstanding immediately prior to the APL Effective Time and held by a New Atlas allocated employee, a non-employee director of ATLS or APL, or a former employee will, as of the APL Effective Time, become fully vested and be cancelled and converted into the right to receive the APL Merger Consideration in respect of each APL common unit underlying the APL phantom unit award.

APL Phantom Unit Awards Held by ATLS Allocated Employees

Each APL phantom unit award that is outstanding immediately prior to the APL Effective Time and held by an ATLS allocated employee will, as of the APL Effective Time, be cancelled and converted into the right to receive: (1) the APL Cash Consideration in respect of each APL common unit underlying the APL phantom unit award and (2) a TRP phantom unit award with respect to a number of TRP units (rounded to the nearest whole unit) equal to the product of (a) number of APL common units underlying the APL phantom unit award, multiplied by (b) the APL Unit Consideration. Each TRP phantom unit award will settle in TRP units upon vesting.

Special Meetings

TRC Special Meeting

Where and when: The TRC special meeting will take place at                     on                     , 2015 at             , local time.

What you are being asked to vote on: At the TRC special meeting, TRC stockholders will vote on the TRC stock issuance proposal and the adjournment proposal.

Who may vote: You may vote at the TRC special meeting if you owned TRC shares at the close of business on the record date,                     , 2015. On that date, there were                     TRC shares outstanding. You may cast one vote for each outstanding TRC share that you owned on the record date.

What vote is needed: Approval of the TRC stock issuance proposal requires the affirmative vote of a majority of the TRC shares present in person or represented by proxy at the TRC special meeting and entitled to

vote thereon. Approval of the adjournment proposal requires the affirmative vote of a majority of the TRC shares present in person or represented by proxy at the TRC special meeting and entitled to vote thereon. Abstentions will have the same effect as votes against the TRC stock issuance proposal and the adjournment proposal. Failures to vote and broker non-votes (if any) will have no effect on the TRC stock issuance proposal and the adjournment proposal.

All of the directors and executive officers of TRC beneficially own, in the aggregate, approximately     % of the outstanding TRC shares as of the record date. Pursuant to voting and support agreements with ATLS, the executive officers of TRC have agreed to vote any TRC shares beneficially owned by them in favor of the TRC stock issuance proposal and the adjournment proposal. The TRC stockholders party to the voting and support agreements beneficially own, in the aggregate, approximately     % of the outstanding TRC shares as of the record date. In addition, we believe that the directors of TRC will vote in favor of the TRC stock issuance proposal and the adjournment proposal.

ATLS Special Meeting

Where and when: The ATLS special meeting will take place at                     on                     , 2015 at         , local time.

What you are being asked to vote on: At the ATLS special meeting, ATLS unitholders will vote on the ATLS Merger proposal and the ATLS compensation proposal. ATLS unitholders also may be asked to consider other matters as may properly come before the meeting. At this time, ATLS knows of no other matters that will be presented for the consideration of its unitholders at the meeting.

Who may vote: You may vote at the ATLS special meeting if you owned ATLS common units at the close of business on the record date,                     , 2015. On that date, there were             ATLS common units outstanding. You may cast one vote for each outstanding ATLS common unit that you owned on the record date.

What vote is needed: Approval of the ATLS Merger proposal requires the affirmative vote of a majority of the outstanding ATLS common units entitled to vote thereon. Approval, on an advisory, non-binding basis, of the ATLS compensation proposal each requires the affirmative vote of the holders of a majority of the outstanding units entitled to vote and represented in person or by proxy at the ATLS special meeting. Abstentions will have the same effect as votes against the ATLS Merger proposal and the ATLS compensation proposal. Failures to vote and broker non-votes (if any) will have the same effect as votes against the ATLS Merger proposal and will have no effect on the ATLS compensation proposal. The vote on the ATLS compensation proposal is a vote separate and apart from the ATLS Merger proposal. Accordingly, you may vote to approve the ATLS Merger proposal and vote not to approve the ATLS compensation proposal and vice versa. Because the vote on the ATLS compensation proposal is advisory in nature only, it will not be binding on ATLS or TRC.

All of the directors and executive officers of ATLS beneficially own, in the aggregate, approximately     % of the outstanding ATLS common units as of the record date. Pursuant to voting and support agreements with TRC, certain directors and officers of ATLS have agreed to vote any ATLS common units beneficially owned by them in favor of the ATLS executive Merger proposal. The ATLS unitholders party to the voting and support agreements beneficially own, in the aggregate, approximately     % of the outstanding ATLS common units as of the record date. In addition, we believe that the directors and executive officers of ATLS who are not party to voting and support agreements will vote in favor of adopting the APL Merger proposal. We also believe that the directors and executive officers of ATLS will vote in favor of adopting the ATLS compensation proposal.

Recommendation to the TRC Stockholders and the TRC Board’s Reasons for the ATLS Merger

At a special board meeting held on October 12, 2014, the TRC Board unanimously determined that the ATLS Merger, the ATLS Merger Agreement, and the transactions contemplated thereby, including the TRC stock issuance, are in the best interests of TRC and the TRC stockholders. The TRC Board unanimously approved the ATLS Merger, the ATLS Merger Agreement and the transactions contemplated thereby, including the TRC stock issuance, and recommends that the holders of TRC shares vote FOR the TRC stock issuance proposal and FOR the adjournment proposal. In the course of reaching its decision to approve the ATLS Merger, the ATLS Merger Agreement and the transactions contemplated thereby, the TRC Board considered a number of factors in its deliberations. For a more complete discussion of these factors, see “The Transactions—Recommendation to the TRC Stockholders and the TRC Board’s Reasons for the ATLS Merger.”

Recommendation to the ATLS Unitholders and the ATLS GP Board’s Reasons for the ATLS Merger

At a special board meeting held on October 12, 2014, the ATLS GP Board unanimously determined that the ATLS Merger, the ATLS Merger Agreement, and the transactions contemplated thereby, are in the best interests of ATLS and the ATLS unitholders. The ATLS GP Board unanimously approved the ATLS Merger, the ATLS Merger Agreement and the transactions contemplated thereby, and recommends that the ATLS unitholders vote FOR the ATLS Merger proposal and FOR the ATLS compensation proposal. In the course of reaching its decision to approve the ATLS Merger proposal, the ATLS GP Board considered a number of factors in its deliberations. For a more complete discussion of these factors, see “The Transactions—Recommendation to the ATLS Unitholders and the ATLS GP Board’s Reasons for the ATLS Merger.”

In considering the recommendation of the ATLS GP Board, ATLS unitholders should be aware that some of ATLS’s directors and executive officers may have interests in the transactions that are different from, or in addition to, the interests they may have as unitholders. See “The Transactions—Interests of Certain Persons in the Transactions.”

Opinion of the TRC Board’s Financial Advisor

On October 12, 2014, Wells Fargo Securities, LLC, which we refer to in this joint proxy statement/prospectus as “Wells Fargo Securities,” rendered its oral opinion to the TRC Board (which was confirmed in writing by delivery of Wells Fargo Securities’ written opinion addressed to the TRC Board dated October 12, 2014), as to, as of October 12, 2014, the fairness, from a financial point of view, to TRC of the ATLS Merger Consideration to be paid and issued by TRC in the ATLS Merger pursuant to the ATLS Merger Agreement.

Wells Fargo Securities’ opinion was for the information of the TRC Board (in its capacity as such) in connection with its evaluation of the ATLS Merger. Wells Fargo Securities’ opinion only addressed the fairness, from a financial point of view, to TRC of the ATLS Merger Consideration to be paid and issued by TRC in the ATLS Merger pursuant to the ATLS Merger Agreement and did not address any other terms, aspects or implications of the ATLS Merger or any agreements, arrangements or understandings entered into in connection therewith or otherwise. The summary of Wells Fargo Securities’ opinion in this joint proxy statement/prospectus is qualified in its entirety by reference to the full text of its written opinion, which is attached as Annex C and describes the procedures followed, assumptions made, qualifications and limitations on the review undertaken and other matters considered by Wells Fargo Securities in connection with the preparation of its opinion. However, neither Wells Fargo Securities’ opinion nor the summary of its opinion and the related analyses set forth in this joint proxy statement/prospectus are intended to be, and do not constitute, a recommendation as to or otherwise address how the members of the TRC Board, the holders of TRC common stock or any other person should vote or act in

respect to the ATLS Merger or any related matter. See “The Transactions—Opinion of the TRC Board’s Financial Advisor.”

Opinions of ATLS’s Financial Advisors

Opinion of Citigroup Global Markets Inc.

In connection with the ATLS Merger, Citigroup Global Markets Inc. (“Citi”), financial advisor to ATLS and APL, delivered a written opinion, dated October 12, 2014, to the ATLS GP Board as to the fairness, from a financial point of view and as of the date of the opinion, to holders of ATLS common units of the ATLS Merger Consideration to be received by such holders pursuant to the ATLS Merger Agreement. The full text of Citi’s written opinion, dated October 12, 2014, which describes the assumptions made, procedures followed, matters considered and limitations on the review undertaken, is attached as Annex D and is incorporated herein by reference. The description of Citi’s opinion set forth below is qualified in its entirety by reference to the full text of Citi’s opinion. Citi’s opinion was provided for the information of the ATLS GP Board (in its capacity as such on behalf of ATLS) in connection with its evaluation of the ATLS Merger Consideration from a financial point of view and did not address any other terms, aspects or implications of the ATLS Merger or the other Transactions. Citi was not requested to consider, and its opinion did not address, the underlying business decision of ATLS or APL to effect the ATLS Merger or any other Transactions, the relative merits of the ATLS Merger or any other Transactions as compared to any alternative business strategies or opportunities that might exist for ATLS or APL or the effect of any other transaction in which ATLS or APL might engage or consider. Citi’s opinion is not intended to be and does not constitute a recommendation as to how any securityholder should vote or act on any matters relating to the proposed ATLS Merger, any other Transactions or otherwise.

Opinion of Deutsche Bank Securities Inc.

Deutsche Bank Securities Inc. (“Deutsche Bank”), one of the financial advisors to ATLS, rendered its written opinion to the ATLS GP Board that, as of October 13, 2014 and based upon and subject to the assumptions, limitations, qualifications and conditions described in Deutsche Bank’s opinion, the ATLS Merger Consideration to be paid to the holders of ATLS common units pursuant to the ATLS Merger Agreement was fair, from a financial point of view, to such holders (excluding TRC and its affiliates).

The full text of Deutsche Bank’s written opinion, dated as of October 13, 2014, which sets forth, among other things, the assumptions made, matters considered and limitations, qualifications and conditions of the review undertaken by Deutsche Bank in connection with the opinion, is attached as Annex E and is incorporated herein by reference in its entirety. The summary of Deutsche Bank’s opinion set forth in this document is qualified in its entirety by reference to the full text of the opinion. Deutsche Bank’s opinion was addressed to, and was for the use and benefit of, the ATLS GP Board in connection with and for the purpose of its evaluation of the ATLS Merger. While Deutsche Bank gave effect to the Spin-Off and the APL Merger in reaching its opinion, Deutsche Bank’s opinion addressed only the fairness of the ATLS Merger Consideration from a financial point of view to the holders of outstanding ATLS common units (excluding TRC and its affiliates) pursuant to the ATLS Merger Agreement. Deutsche Bank did not consider, and its opinion did not address, the relative fairness of the ATLS Merger Consideration as compared with the APL Merger Consideration. Nor did Deutsche Bank express an opinion, and its opinion did not constitute a recommendation, as to how any holder of ATLS common units should vote with respect to the ATLS Merger or any other matter. Deutsche Bank’s opinion was limited to the fairness of the ATLS Merger Consideration, from a financial point of view, to the holders of ATLS common units (excluding TRC and its affiliates) as of the date of the opinion. Deutsche Bank expressed no opinion as to the merits of the underlying decision by ATLS to engage in the ATLS Merger or the relative merits of the ATLS Merger (or any other transaction contemplated by the Separation Agreement or the APL Merger

Agreement) as compared to any alternative transactions or business strategies. See “The Transactions—Opinions of ATLS’s Financial Advisors.”

Interests of Certain Persons in the Transactions

In considering the recommendation of the ATLS GP Board with respect to the ATLS Merger Agreement, ATLS unitholders should be aware that some of ATLS’s directors and executive officers have interests in the transaction that are different from, or in addition to, the interests of ATLS’s unitholders generally, including, among others:

These interests are discussed in more detail in the section entitled “The Transactions—Interests of Certain Persons in the Transaction.” The ATLS GP Board was aware of these different or additional interests, and considered them along with other matters in approving the ATLS Merger Agreement and the Transactions.

The Transaction Agreements

The ATLS Merger Agreement

Conditions to Consummation of the ATLS Merger

The obligations of TRC and ATLS to effect the ATLS Merger are subject to the satisfaction or waiver (if waiver is permitted by applicable law) of the following conditions:

The obligations of ATLS to effect the ATLS Merger are subject to the satisfaction or waiver of the following additional conditions:

The obligations of TRC to effect the ATLS Merger are subject to the satisfaction or waiver of the following additional conditions, at or prior to the closing:

No Solicitation by ATLS of Alternative Proposals

The ATLS Merger Agreement contains detailed provisions prohibiting ATLS GP and ATLS from seeking an alternative proposal to the ATLS Merger (as defined under “The Transaction Agreements—The ATLS Merger Agreement—No Solicitation by ATLS of Alternative Proposals”). Under these “no solicitation” provisions, neither ATLS GP nor ATLS will, and each of ATLS and ATLS GP will cause ATLS’s subsidiaries and the New Atlas Companies not to, and use reasonable best efforts to cause its and the subsidiaries’ and New Atlas Companies’ officers, directors, managers, members, employees and other representatives not to, directly or indirectly,

In addition, the ATLS Merger Agreement requires that ATLS GP and ATLS will, and will use reasonable best efforts to cause its and its subsidiaries’ and the New Atlas Companies’ representatives to, immediately cease and cause to be terminated any discussions or negotiations with any person (other than Targa entities and their respective representatives) conducted on or prior to October 13, 2014 with respect to any alternative proposal (which, for this purpose, need not have been an unsolicited proposal) and request of each such person that executed a confidentiality agreement with ATLS with respect to any alternative proposal (which, for this purpose, need not have been an unsolicited proposal) in the six months prior to October 13, 2014 and is in possession of confidential information about ATLS GP, ATLS or any of their subsidiaries, the return or destruction of all such confidential information in accordance with the terms of the confidentiality agreement with such person.

Notwithstanding these restrictions, the ATLS Merger Agreement provides that, at any time prior to ATLS unitholders voting in favor of adopting the ATLS Merger Agreement, if ATLS or ATLS GP receives an alternative proposal that was not solicited after the execution of the ATLS Merger Agreement, that the ATLS GP Board believes is bona fide and that did not result from a violation of the no solicitation restrictions described above, and (after consultation with its financial advisors and outside legal counsel) the ATLS GP Board determines in good faith that such alternative proposal could result in a superior proposal (as defined under “The Transaction Agreements—The ATLS Merger Agreement—No Solicitation by ATLS of Alternative Proposals”), ATLS may (A) furnish information, including non-public information, with respect to it and its subsidiaries, and afford access to the business, properties, books and records of ATLS and its subsidiaries, to the person making such alternative proposal and such person’s representatives and (B) enter into and participate in discussions or negotiations with the person making such alternative proposal and its representatives, provided that ATLS comply with certain provisions of the ATLS Merger Agreement as described under “The Transaction Agreements—The ATLS Merger Agreement—No Solicitation by ATLS of Alternative Proposals.”

Change in ATLS GP Board Recommendation; Termination for Superior Proposal

The ATLS Merger Agreement generally provides that, subject to the exceptions described below, the ATLS GP Board will not effect a ATLS change in recommendation (as defined under “The Transaction Agreements—The ATLS Merger Agreement—Change in ATLS GP Board Recommendation”). Notwithstanding anything in the ATLS Merger Agreement to the contrary, if (i) ATLS receives a written, unsolicited alternative proposal (and such proposal is not withdrawn) that the ATLS GP Board believes is bona fide, (ii) such alternative proposal did not result, directly or indirectly, from a violation of the no solicitation provisions described above and (iii) the

ATLS GP Board determines, after consultation with its financial advisors and outside legal counsel, that such alternative proposal constitutes a superior proposal, then the ATLS GP Board may at any time prior to obtaining the ATLS unitholder approval, effect an ATLS change in recommendation or terminate the ATLS Merger Agreement to enter into a definitive agreement in respect of the superior proposal; provided, however, that the ATLS GP Board may not take such action pursuant to the foregoing unless it complies with certain provisions of the ATLS Merger Agreement as described under “The Transaction Agreements—The ATLS Merger Agreement—Change in ATLS GP Board Recommendation.”

Other than in connection with an alternative proposal, the ATLS Merger Agreement also permits the ATLS GP Board to make an ATLS change in recommendation in response to an ATLS intervening event (as defined under “The Transaction Agreements—The ATLS Merger Agreement—Change in ATLS GP Board Recommendation”) at any time prior to obtaining the approval of the ATLS unitholders of the ATLS Merger Agreement, but only if it complies with certain provisions of the ATLS Merger Agreement as described under “The Transaction Agreements—The ATLS Merger Agreement—Change in ATLS GP Board Recommendation.”

Change in TRC Board Recommendation

The ATLS Merger Agreement generally provides that the TRC Board will not effect a TRC change in recommendation (as defined under “The Transaction Agreements—The ATLS Merger Agreement—Change in TRC Board Recommendation”).

Notwithstanding anything in the ATLS Merger Agreement to the contrary, the ATLS Merger Agreement permits the TRC Board to make a TRC change in recommendation in response to a TRC intervening event (as defined under “The Transaction Agreements—The ATLS Merger Agreement—Change in TRC Board Recommendation”) at any time prior to obtaining the approval of the ATLS unitholders of the ATLS Merger Agreement, but only if TRC complies with certain requirements set forth under “The Transaction Agreements—The ATLS Merger Agreement—Change in TRC Board Recommendation.”

Termination of the ATLS Merger Agreement

Either TRC or ATLS may terminate the ATLS Merger Agreement at any time prior to the closing:

In addition, TRC may terminate the ATLS Merger Agreement:

In addition, ATLS may terminate the ATLS Merger Agreement:

Termination Fees and Expenses

The ATLS Merger Agreement provides for certain termination rights for both ATLS and TRC, including provisions permitting either ATLS or TRC to terminate the ATLS Merger Agreement upon the termination of the APL Merger Agreement. The ATLS Merger Agreement further provides that upon termination of the APL Merger Agreement under certain circumstances, ATLS or TRC, as applicable, will be obligated to pay the other party one of the following (depending on circumstances of termination): (1) a termination fee of $53.4 million, (2) a payment in respect of the other party’s expenses of $17.8 million, or (3) fifty percent (50%) of such termination fee or expense payment.

The APL Merger Agreement

Conditions to Consummation of the APL Merger

The obligations of TRP and APL to effect the APL Merger are subject to the satisfaction or waiver (if waiver is permitted by applicable law) of the following conditions:

The obligations of APL to effect the APL Merger are subject to the satisfaction or waiver of the following additional conditions:

The obligations of TRP to effect the APL Merger are subject to the satisfaction or waiver of the following additional conditions, at or prior to the closing:

No Solicitation by APL of Alternative Proposals

The APL Merger Agreement contains detailed provisions prohibiting APL GP and APL from seeking an alternative proposal to the APL Merger (as defined under “The Transaction Agreements—The APL Merger Agreement—No Solicitation by APL of Alternative Proposals”). Under these “no solicitation” provisions, neither APL GP nor APL will, and each of APL and APL GP will cause APL’s subsidiaries not to, and use reasonable best efforts to cause its and the subsidiaries’ officers, directors, managers, members, employees and other representatives not to, directly or indirectly,

In addition, the APL Merger Agreement requires that APL GP and APL will, and will use reasonable best efforts to cause its and its subsidiaries’ representatives to, immediately cease and cause to be terminated any discussions or negotiations with any person (other than APL entities and their respective representatives) conducted on or prior to October 13, 2014 with respect to any alternative proposal (which, for this purpose, need not have been an unsolicited proposal) and request of each such person that executed a confidentiality agreement with APL with respect to any alternative proposal (which, for this purpose, need not have been an unsolicited proposal) in the six months prior to October 13, 2014 and is in possession of confidential information about APL GP, APL or any of their subsidiaries, the return or destruction of all such confidential information in accordance with the terms of the confidentiality agreement with such person.

Notwithstanding these restrictions, the APL Merger Agreement provides that, at any time prior to APL unitholders voting in favor of adopting the APL Merger Agreement, if APL receives an alternative proposal that was not solicited after the execution of the APL Merger Agreement, that the APL GP Board (upon the recommendation of the APL GP Conflicts Committee) believes is bona fide and that did not result from a violation of the no solicitation restrictions described above, and (after consultation with its financial advisors and outside legal counsel) the APL GP Board (upon the recommendation of the APL GP Conflicts Committee) determines in good faith that such alternative proposal could result in a superior proposal (as defined under “The Transaction Agreements—The APL Merger Agreement—No Solicitation by APL of Alternative Proposals”), APL may (A) furnish information, including non-public information, with respect to it and its subsidiaries to, and afford access to the business, properties, books and records of APL and its subsidiaries, to the person making such alternative proposal and such person’s representatives and (B) enter into and participate in discussions or negotiations with the person making such alternative proposal and its representatives (which was not solicited after the execution of the APL Merger Agreement and that did not result from a violation of the no solicitation restrictions described above), provided that APL comply with certain provisions of the APL Merger Agreement as described under “The Transaction Agreements—The APL Merger Agreement—No Solicitation by APL of Alternative Proposals.”

Change in APL GP Board Recommendation

The APL Merger Agreement generally provides that, subject to certain exceptions described below, neither the APL GP Board nor the APL GP Conflicts Committee will effect a APL change in recommendation (as defined under “The Transaction Agreements—The APL Merger Agreement—Change in APL GP Board Recommendation”). Notwithstanding anything in the APL Merger Agreement to the contrary, if (i) APL receives a written, unsolicited alternative proposal (and such proposal is not withdrawn) that the APL GP Board (upon the recommendation of the APL GP Conflicts Committee) believes is bona fide, (ii) such alternative proposal did not result, directly or indirectly, from a violation of the no solicitation provisions described above and (iii) the APL GP Board (upon the recommendation of the APL GP Conflicts Committee) determines, after consultation with its financial advisors and outside legal counsel, that such alternative proposal constitutes a superior proposal, then the APL GP Board (upon the recommendation of the APL GP Conflicts Committee) may at any time prior to obtaining the APL unitholder approval, effect an APL change in recommendation; provided, however, that the APL GP Board may not take such action pursuant to the foregoing unless unless it complies with certain provisions of the APL Merger Agreement as described under “The Transaction Agreements—The APL Merger Agreement—Change in APL GP Board Recommendation.”

Other than in connection with an alternative proposal, the APL Merger Agreement also permits the APL GP Board (upon the recommendation of the APL GP Conflicts Committee) to make an APL change in recommendation in response to an APL intervening event (as defined under “The Transaction Agreements—The APL Merger Agreement—Change in APL GP Board Recommendation”) at any time prior to obtaining the approval of the APL unitholders of the APL Merger Agreement, but only if it complies with certain provisions of the APL Merger Agreement as described under “The Transaction Agreements—The APL Merger Agreement—Change in APL GP Board Recommendation.”

Termination of the APL Merger Agreement

Either TRP or APL may terminate the APL Merger Agreement at any time prior to the closing:

In addition, TRP may terminate the APL Merger Agreement:

In addition, APL may terminate the APL Merger Agreement if a TRP terminable breach has occurred (as defined under “The Transaction Agreements—The APL Merger Agreement—Termination of the APL Merger Agreement”); provided that APL shall not have the right to terminate the APL Merger Agreement pursuant to a TRP terminable breach if APL is then in material breach of any of its representations, warranties, covenants or agreements set forth in the APL Merger Agreement.

Termination Fees and Expenses

The APL Merger Agreement provides for certain termination rights for both APL and TRP, including provisions permitting either APL or TRP to terminate the APL Merger Agreement upon the termination of the ATLS Merger Agreement. The APL Merger Agreement further provides that upon termination of the APL Merger Agreement under certain circumstances, APL or TRP, as applicable, will be obligated to pay the other party one of the following (depending on circumstances of termination): (1) a termination fee of $122.9 million, (2) a payment in respect of the other parties’ expenses of $20.45 million or (3) or fifty percent (50%) of such termination fee or expense payment.

Voting Agreements

ATLS Merger Voting Agreements

In connection with the parties’ entry into the ATLS Merger Agreement, TRC entered into voting and support agreements, dated October 13, 2014, with certain directors and officers of ATLS pursuant to which such directors and officers of ATLS have agreed to vote any ATLS common units beneficially owned by them in favor of the ATLS Merger proposal. The ATLS unitholders party to the voting and support agreements beneficially own, in the aggregate, approximately     % of the outstanding ATLS common units as of the record date.

In addition, ATLS entered into voting and support agreements, dated October 13, 2013, with the executive officers of TRC pursuant to which such executive officers of TRC have agreed to vote any TRC shares beneficially owned by them in favor of the TRC stock issuance proposal and the adjournment proposal. The TRC stockholders party to the voting and support agreements beneficially own, in the aggregate, approximately     % of the outstanding TRC shares as of the record date.

APL Merger Voting Agreements

In connection with the parties’ entry into the APL Merger Agreement, TRP entered into voting and support agreements, dated October 13, 2014, with certain managers and officers of APL pursuant to which such managers and officers of APL have agreed to vote any APL common units beneficially owned by them in favor of approving and adopting the APL Merger Agreement and approving the APL Merger. The APL unitholders party to the voting and support agreements beneficially own, in the aggregate, approximately     % of the outstanding APL common units as of the record date.

Separation Agreement

Subject to the terms and conditions set forth in the ATLS Merger Agreement, ATLS has agreed that, prior to the closing of the ATLS Merger, it will enter into the Separation Agreement, in substantially the form attached to the ATLS Merger Agreement, pursuant to which ATLS will transfer its assets and liabilities other than those related to its “Atlas Pipeline Partners” segment to New Atlas and, immediately prior to the ATLS Merger, effect a pro rata distribution to the ATLS unitholders of New Atlas common units representing a 100% interest in New Atlas. The Separation Agreement sets forth New Atlas’s agreements with ATLS regarding the principal actions to be taken in connection with these transactions and other agreements that will govern aspects of New Atlas’s relationship with ATLS following the Spin-Off. New Atlas has filed a registration statement on Form 10, including an information statement, with the SEC in connection with the Spin-Off. For a more detailed description of the Separation Agreement, please refer to the Form 10.

Employee Matters Agreement

ATLS has agreed that, prior to the closing of the ATLS Merger, it will enter into the Employee Matters Agreement, in substantially the form attached the Separation Agreement, to allocate liabilities and responsibilities relating to employment matters, employee compensation and benefits plans and programs, and other related matters. The Employee Matters Agreement will govern certain compensation and employee benefit obligations with respect to the current and former employees and non-employee directors of New Atlas and ATLS.

Unless otherwise specified, ATLS will be responsible for liabilities associated with ATLS allocated employees and New Atlas will be responsible for liabilities associated with New Atlas allocated employees.

IDR Giveback Amendment

Pursuant to the APL Merger Agreement, TRC has agreed to cause TRP GP to enter into an amendment to the TRP partnership agreement, which we refer to as the IDR Giveback Amendment, in substantially the form attached to the APL Merger Agreement, in order to reduce aggregate distributions to TRC, as the holder of TRP’s IDRs, by (a) $9,375,000 per quarter during the first four quarters following the APL Effective Time, (b) $6,250,000 per quarter for the next four quarters, (c) $2,500,000 per quarter for the next four quarters and (d) $1,250,000 per quarter for the next four quarters, with the amount of such reductions to be distributed pro rata to the holders of TRP outstanding common units.

Reimbursement Letter

In connection with their entry into the ATLS Merger Agreement and the APL Merger Agreement, ATLS and APL entered into a letter agreement, dated October 13, 2014, providing that, in certain circumstances, ATLS or APL will reimburse the other for $17.8 million of the termination fee payable by such party relating to a termination of the APL Merger Agreement or ATLS Merger Agreement, as applicable, because the other merger agreement is terminated:

Notwithstanding the foregoing, neither ATLS nor APL shall be obligated to make payments pursuant to the letter agreement in excess of $17.8 million in the aggregate.

Non-Competition Agreements

In connection with entering into the ATLS Merger Agreement and the APL Merger Agreement, TRC and TRP entered into a confidentiality, non-competition and non-solicitation agreement with each of Edward E. Cohen, Jonathan Z. Cohen, and Eugene N. Dubay. Each such agreement generally requires that, for a period of 18 months following the completion of the Atlas Mergers, such person refrain from engaging in the following activities in certain geographic areas: (1) engaging in certain activities related to the midstream businesses in certain geographic areas, (2) soliciting for employment or hiring individuals employed by the Midstream Companies, subject to certain exceptions, and (3) causing, soliciting or knowingly encouraging certain business relations of the Midstream Companies to cease doing business with the Midstream Companies.

Material U.S. Federal Income Tax Consequences of the ATLS Merger

The receipt of TRC shares and cash in exchange for ATLS common units pursuant to the ATLS Merger will be a taxable transaction for U.S. federal income tax purposes to U.S. holders (as defined in “Material U.S. Federal Income Tax Consequences”). A U.S. holder who receives TRC shares and cash in exchange for ATLS common units pursuant to the ATLS Merger will recognize gain or loss in an amount equal to the difference between (i) the “amount realized,” which is the sum of (A) the amount of cash received, (B) the fair market value of TRC shares received, and (C) such U.S. holder’s share of ATLS’s nonrecourse liabilities immediately prior to the ATLS Merger; and (ii) such U.S. holder’s adjusted tax basis in the ATLS common units exchanged therefor (which includes any remaining basis attributable to such U.S. holder’s share of ATLS’s nonrecourse liabilities immediately prior to the ATLS Merger).

Gain or loss recognized by a U.S. holder will generally be taxable as capital gain or loss. However, a portion of this gain or loss, which portion is likely to be substantial, will be separately computed and taxed as ordinary income or loss under Section 751 of the Internal Revenue Code of 1986, as amended (the “Code”) to the extent attributable to assets giving rise to depreciation recapture or other “unrealized receivables” or to “inventory items” owned by ATLS and its subsidiaries, even if the ATLS unitholder’s aggregate adjusted basis in its ATLS common units exceeds the amount realized in the exchange. Consequently, a U.S. holder may recognize both ordinary income and capital loss upon the exchange of ATLS common units in the ATLS Merger. Passive losses that were not deductible by a U.S. holder in prior taxable periods because they exceeded a U.S. holder’s share of

ATLS’s income may become available to offset a portion of the gain recognized by such U.S. holder. In addition, certain ATLS unitholders may be subject to the 3.8% net investment income tax on unearned income in respect of any net gain from the exchange.

The U.S. federal income tax consequences of the ATLS Merger to an ATLS unitholder will depend on such unitholder’s own personal tax situation. Accordingly, we strongly urge you to consult your tax advisor for a full understanding of the particular tax consequences of the ATLS Merger to you. See “Material U.S. Federal Income Tax Consequences.”

Other Information Related to the Transactions

No Appraisal Rights

Neither TRC stockholders nor ATLS unitholders are entitled to appraisal rights in connection with the APL Merger under applicable law or contractual appraisal rights under TRC’s organizational documents, the ATLS partnership agreement or the ATLS Merger Agreement.

Antitrust and Regulatory Matters

Under the HSR Act, certain transactions, including the Atlas Mergers, may not be completed until notifications have been given and information furnished to the Antitrust Division and the FTC, and all statutory waiting period requirements under the HSR Act have been satisfied. On October 24, 2014, TRP and APL filed the requisite notification and report forms under the HSR Act with the DOJ and FTC. On November 4, 2014, TRP and APL received notice of early termination of the waiting period under the HSR Act. The ATLS Merger is not separately reportable under the HSR Act.

Listing of TRC Shares to be Issued in the ATLS Merger; Delisting and Deregistration of ATLS Common Units

TRC expects to obtain approval to list, on the NYSE, the TRC shares to be issued pursuant to the ATLS Merger Agreement, which approval is a condition to the ATLS Merger. Upon completion of the ATLS Merger, ATLS common units currently listed on the NYSE will cease to be listed on the NYSE and will be subsequently deregistered under the Exchange Act.

Accounting Treatment of the Atlas Mergers

In conformity with accounting principles generally accepted in the United States and in accordance with the Financial Accounting Standards Board’s Accounting Standards Codification Topic 805—Business Combinations, TRC and TRP will account for the ATLS Merger and the APL Merger, respectively, as an acquisition of a business.

Pending Litigation

In October and November 2014, four public unitholders of APL filed putative class action lawsuits against APL, ATLS, APL GP, its managers, TRC, TRP, TRP GP and MLP Merger Sub. In October and November 2014, two public unitholders of ATLS filed putative class action lawsuits against ATLS, ATLS GP, its managers, TRC and GP Merger Sub. The plaintiffs allege a variety of causes of action challenging the Atlas Mergers. Targa and Atlas cannot predict the outcome of these or any other lawsuits that might be filed subsequent to the date of the filing of this joint proxy statement/prospectus, nor can Targa or Atlas predict the amount of time and expense that will be required to resolve these lawsuits. Targa, Atlas and the other defendants named in these lawsuits intend to defend vigorously against these actions.

Comparison of the Rights of TRC Stockholders and ATLS Unitholders

A limited partnership is inherently different from a corporation. Ownership interests in a limited partnership are therefore fundamentally different from ownership interests in a corporation. ATLS unitholders will own TRC common stock following the completion of the ATLS Merger, and their rights associated with the TRC common stock will be governed by TRC’s organizational documents and Delaware corporation law, which differ in a number of respects from the ATLS partnership agreement and Delaware Revised Uniform Limited Partnership Act (the “Delaware LP Act”).

Summary of Risk Factors

You should consider carefully all the risk factors together with all of the other information included in this joint proxy statement/prospectus before deciding how to vote. The risks related to the Atlas Mergers and the related transactions, Targa’s business, TRC shares and risks resulting from TRC’s organizational structure are described under the caption “Risk Factors” beginning on page 39 of this joint proxy statement/prospectus. Some of these risks include, but are not limited to, those described below:

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF TRC

The following selected historical consolidated financial data as of and for the nine months ended September 30, 2014 and September 30, 2013 are derived from TRC’s unaudited consolidated financial statements and as of and for each of the years ended December 31, 2013, 2012, 2011, 2010, and 2009 are derived from TRC’s audited consolidated financial statements. You should read the following data in conjunction with “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and the consolidated financial statements and the related notes thereto set forth in TRC’s Annual Report on Form 10-K for the year ended December 31, 2013 and its Quarterly Report on Form 10-Q for the quarter ended September 30, 2014, which are incorporated by reference into this joint proxy statement/prospectus. See “Where You Can Find More Information.” You should not assume the results of operations for any past period indicate results for any future period.

During the third quarter of 2014, TRP concluded that certain prior period buy-sell transactions related to the marketing of NGL products were incorrectly reported on a gross basis as Revenues and Product Purchases in its previous Consolidated Statements of Operations. Generally accepted accounting principles require that such transactions that involve purchases and sales of inventory with the same counterparty that are legally contingent or in contemplation of one another be reported as a single transaction on a combined net basis.

TRP concluded that these misclassifications were not material to any of the periods affected. However, TRP has revised previously reported revenues and product purchases to correctly report NGL buy-sell transactions on a net basis. Accordingly, Revenues and Product Purchases reported in TRP’s Form 10-K filed on February 14, 2014 will be reduced by equal amounts as presented in the following tables. There is no impact on previously reported net income, cash flows, financial position or other profitability measures.

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF ATLS

The following selected historical consolidated financial data as of and for the nine months ended September 30, 2014 and September 30, 2013 are derived from ATLS’ unaudited consolidated financial statements and as of and for each of the years ended December 31, 2013, 2012, 2011, 2010, and 2009 are derived from ATLS’s audited consolidated financial statements. You should read the following data in conjunction with “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and the consolidated financial statements and the related notes thereto set forth in ATLS’s Annual Report on Form 10-K for the year ended December 31, 2013 and its Quarterly Report on Form 10-Q for the quarter ended September 30, 2014, which are incorporated by reference into this joint proxy statement/prospectus. See “Where You Can Find More Information.” You should not assume the results of operations for any past period indicate results for any future period.

SELECTED UNAUDITED PRO FORMA CONDENSED CONSOLIDATED FINANCIAL INFORMATION

The following table sets forth selected unaudited pro forma condensed combined financial information for TRC after giving effect to the Transactions The selected unaudited pro forma condensed combined financial information is derived from the unaudited pro forma condensed combined financial statements included in this joint proxy statement/prospectus. For a complete discussion of the pro forma adjustments underlying the amounts in the table below, please read the section titled “Unaudited Pro Forma Condensed Combined Financial Statements” beginning on page F-1.

COMPARATIVE PER SHARE AND PER UNIT INFORMATION

The following table sets forth (i) historical per share information of TRC, (ii) the unaudited pro forma per share information of TRC after giving pro forma effect to the proposed ATLS Merger and the transactions contemplated thereby, including TRC’s issuance of 0.1809 of a share of TRC common stock for each outstanding ATLS common unit (other than certain common units held by TRC or ATLS or their wholly owned subsidiaries, which will be cancelled) and (iii) the historical and equivalent pro forma per share information for ATLS.

You should read this information in conjunction with (i) the summary historical financial information included elsewhere in this joint proxy statement/prospectus, (ii) the historical consolidated financial statements of ATLS and TRC and related notes that are incorporated by reference in this joint proxy statement/prospectus and (iii) the “Unaudited Pro Forma Condensed Consolidated Financial Statements” and related notes included elsewhere in this joint proxy statement/prospectus. The unaudited pro forma per share and unit information does not purport to represent what the actual results of operations of ATLS and TRC would have been had the proposed ATLS Merger been completed in another period or to project ATLS’s and TRC’s results of operations that may be achieved if the proposed ATLS Merger is completed.

MARKET PRICES AND DIVIDEND AND DISTRIBUTION INFORMATION

TRC shares are traded on the NYSE under the ticker symbol “TRGP” and the ATLS common units are traded on the NYSE under the ticker symbol “ATLS.” The following table sets forth, for the periods indicated, the range of high and low sales prices per unit for TRC shares and ATLS common units, on the NYSE composite tape, as well as information concerning quarterly cash dividends declared paid on the TRC shares and cash distributions declared and paid on the ATLS common units. The sales prices are as reported in published financial sources.

The last reported sale price of ATLS common units on the NYSE on October 10, 2014, the last trading day before TRC announced the execution of the ATLS Merger Agreement, was $32.41. The last reported sale price of TRC shares on the NYSE on October 10, 2014, the last trading day before TRC announced the execution of the ATLS Merger Agreement, was $121.65. The last reported sale price of ATLS common units on the NYSE on                     , 2015, the latest practicable trading day prior to the printing of this joint proxy statement/prospectus, was $            . The last reported sale price of TRC shares on the NYSE on                     , 2015, the latest practicable trading day prior to the printing of this joint proxy statement/prospectus, was $        .

As of                     , 2015, the record date for the TRC special meeting, TRC had             shares outstanding held by approximately             holders of record. TRC intends to pay to its stockholders, on a quarterly basis, dividends equal to the cash it receives from its TRP distributions, less reserves for expenses, future dividends and other uses of cash. If TRP is successful in implementing its business strategy and increasing distributions to its partners, TRC would generally expect to increase dividends to its stockholders, although the timing and amount of any such increased dividends may not necessarily be comparable to any increased TRP distributions. TRC cannot guarantee that any dividends will be declared or paid in the future.

As of                     , 2015, the record date for the ATLS special meeting, ATLS had             common units outstanding held by approximately         holders of record. The ATLS partnership agreement requires it to

distribute all of its “available cash,” as defined in its partnership agreement, within 50 days after the end of each quarter. The payment of quarterly cash distributions by ATLS in the future will depend on the amount of its “available cash” at the end of each quarter.

TRP common units are traded on the NYSE under the ticker symbol “NGLS” and the APL common units are traded on the NYSE under the ticker symbol “APL.” The following table sets forth, for the periods indicated, the range of high and low sales prices per unit for TRP common units and APL common units, on the NYSE composite tape, as well as information concerning quarterly cash distributions declared and paid on those units. The sales prices are as reported in published financial sources.