Notice of annual meeting of stockholders

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE ATI ANNUAL MEETING OF STOCKHOLDERS TO BE HELD ON FRIDAY, MAY 6, 2016.

The proxy statement, proxy card and 2015 annual report of Allegheny Technologies Incorporated are available for review at: http://www.envisionreports.com/ATI

2 \    ATI 2016 Proxy Statement

Table of contents

ATI 2016 Proxy Statement    / 3

Annual meeting of stockholders

Agenda for annual meeting and voting

Director nominees – Class II – Term to expire in 2019

4 \    ATI 2016 Proxy Statement

Corporate Governance Highlights

Our commitment to good corporate governance is illustrated by the following practices:

ATI 2016 Proxy Statement    / 5

6 \    ATI 2016 Proxy Statement

Executive Compensation And Governance Program Changes (2011-2016)

ATI 2016 Proxy Statement    / 7

8 \    ATI 2016 Proxy Statement

2015 Business Performance – Executing our long-term growth strategy

2015 was a difficult year for ATI but one from which we aim to emerge a stronger, leaner and more nimble company. While our financial performance in 2015 was disappointing, we continued to focus on strategic initiatives designed to position ATI for improved financial performance and long-term profitable growth. Throughout 2015, we continued our journey of Building the World’s Best Specialty Materials & Components Company^TM. These actions included:

ATI’s business is cyclical, as are the end markets that use our products. In 2015, ATI’s stock price declined significantly, by over 67%, due to weak demand and historically low base prices for our commodity stainless steel sheet products driven mainly by global excess capacity and exacerbated by falling nickel prices throughout the year. These factors resulted in historic low transaction prices for commodity stainless steel sheet products. In addition, due to falling prices for crude oil and natural gas, demand for our products from the oil and gas market, which is ATI’s second largest end market weakened significantly. Other manufacturing companies, specifically those in steel, metals and mining, were similarly affected. While earnings and stockholder returns are depressed during a down business cycle, such as 2015, our actions to improve and enhance ATI’s manufacturing capabilities through capital investments, cost reduction and productivity improvements, restructuring our businesses, and repositioning ATI to be more focused on growing global markets using ATI’s more differentiated high-value products enables ATI to optimize returns as business conditions and end market demand improve.

Our Compensation Philosophy – Pay for Performance

The overriding principle in designing ATI’s executive compensation program is to drive our long-term strategic vision, and to ensure that the program is aligned with our pay-for-performance philosophy. It is designed to reward executive management based on company performance, create long-term stockholder value and attract and retain key employees.

ATI 2016 Proxy Statement    / 9

Paying for performance is a key attribute of ATI’s compensation philosophy. As such, a significant portion of the NEOs’ compensation is subject to the achievement of rigorous performance goals and, therefore, is “at risk.”

The following shows target and realizable pay to the CEO over the past three-years in terms of total compensation, annual cash incentive, and long-term incentives. Realizable pay is well below targeted amounts.

* The CEO was paid no incentive award under the Annual Incentive Plan for 2013 and 2015.

10 \    ATI 2016 Proxy Statement

Total Realized Compensation

The Personnel & Compensation Committee views the amounts in the Summary Compensation Table as the target compensation opportunity for each NEO under the executive compensation program. When making determinations and awards under the plans, the Committee looks to the actual dollar value of awards to be delivered to the NEOs in any given year, as illustrated by the Total Realized Compensation figures below.

Total Realized Compensation is calculated as follows:

ATI 2016 Proxy Statement    / 11

Item 1 – Election of Directors

The Board of Directors has nominated four directors for election. Richard J. Harshman, Carolyn Corvi, Barbara S. Jeremiah and John D. Turner are standing for election to the Board as Class II directors for a three-year term expiring in 2019. If Item 2 – Approval of Amendments to the Certificate of Incorporation to Declassify the Board of Directors is approved by the requisite number of votes, declassification of the Board of Directors would be phased in over a three-year period. In accordance with Delaware corporate law, declassification of the board would not result in the curtailment of any incumbent director’s term of office prior to expiration of the term. For more information, please see Item 2.

Plurality Voting: Directors are elected by a plurality of the votes cast. This means that the four individuals nominated for election to the Board of Directors who receive the most “FOR” votes (among votes properly cast in person, electronically, telephonically or by proxy) will be elected.

Director Resignation Policy: While directors are elected by a plurality of the votes cast, our Bylaws include a director resignation policy. This policy states that in an uncontested election, if any director nominee receives a greater number of votes “WITHHELD” from his or her election, as compared to votes “FOR” such election, the director nominee must tender his or her resignation. The Nominating and Governance Committee of the Board is required to make recommendations to the Board of Directors regarding any such tendered resignation. The Board of Directors will act on the tendered resignation within 90 days from the certification of the vote and will publicly disclose its decision, including its rationale.

Only votes “FOR” or “WITHHELD” are counted in determining whether a plurality has been cast in favor of a director nominee; abstentions are not counted for purposes of the election of directors. If you withhold authority to vote with respect to the election of some or all of the nominees, your shares will not be voted with respect to those nominees indicated. For a “WITHHOLD” vote, your shares will be counted for purposes of determining whether there is a quorum and will have a similar effect as a vote against that director nominee for purposes of our director resignation policy.

If a nominee becomes unable to serve, the proxies will vote for a Board-designated substitute or the Board may reduce the number of directors. The Company has no reason to believe that any of the nominees for election will be unable to serve.

Director Terms

The directors currently are divided into three classes and the directors in each class generally serve for a three-year term unless the director is unable to serve due to death, retirement or disability. The term of one class of directors currently expires each year at the annual meeting of stockholders. The Board may fill a vacancy by electing a new director to the same class as the director being replaced or by effectively reassigning a director from another class. The Board may also create a new director position in any class and elect a director to hold the newly created position. It is expected that new directors elected by the Board will stand for election by the stockholders at the next annual meeting.

Our Director Nomination Process

The Board is responsible for recommending director nominees to the stockholders and for selecting directors to fill vacancies between stockholder meetings. The Nominating and Governance Committee recommends candidates to the Board.

The Committee considers director candidates suggested by members of the Committee, other directors, senior management and stockholders. For information on how to submit a candidate for consideration, please see

12 \    ATI 2016 Proxy Statement

“2017 Annual Meeting and Stockholder Proposals”. Preliminary interviews of director candidates may be conducted by the Chair of the Nominating and Governance Committee or, at her request, any other member of the Committee or the Chairman of the Board. Background material pertaining to director candidates is distributed to the Committee for review. The Chair of the Committee and other Committee members, directors and key senior management interviews director candidates who merit further consideration. The Nominating and Governance Committee consider the results of these interviews in its deliberations.

Board Diversity is one of many criteria considered by the Board when evaluating candidates, though the Board does not have a formal policy regarding diversity. A key factor in determining director nominees is building a cognitively diverse board representing a wide breadth of experience and perspectives.

In accordance with our mandatory retirement policy for directors, if a director will reach his or her 72nd birthday during the director’s subsequent term, the Nominating and Governance Committee should take this fact into account in determining whether to recommend the nomination of the director. New directors added to the Board or to fill vacancies are expected to stand for re-election at the next annual meeting of stockholders.

ATI 2016 Proxy Statement    / 13

In evaluating the needs of the Board, the Nominating and Governance Committee considers the qualifications of sitting directors and consults with other members of the Board (including as part of the Board’s annual self-evaluation), the Chairman, President and Chief Executive Officer, and other members of executive management. At a minimum, all recommended candidates must exemplify the highest standards of personal and professional integrity, meet any required independence standards, and be willing and able to constructively participate in and contribute to Board and committee meetings. Additionally, the Committee conducts individual reviews of current directors whose terms are nearing expiration, but who may be proposed for re-election, in light of the considerations described above and their past contributions to the Board.

Director Skills Summary

Our 2016 Director Nominees and Continuing Directors

The Board of Directors determined that each of the four director nominees qualifies for election under the criteria for evaluation of directors. The Board of Directors determined that Mses. Corvi and Jeremiah and that Mr. Turner qualify as independent directors under applicable rules and regulations and our categorical Board independence standards.

All of our directors bring to our Board a wealth of leadership experience derived from their service in executive and managerial roles and also extensive board experience. Background information about the nominees and the continuing directors, including their business experience and directorships held during the past five years, and certain individual qualifications and skills of our directors that contribute to the Board’s effectiveness as a whole, are described in the following pages.

14 \    ATI 2016 Proxy Statement

Nominees – Class II – Term to Expire at the 2019 Annual Meeting

ATI 2016 Proxy Statement    / 15

Continuing Directors – Class III – Term to Expire at the 2017 Annual Meeting

16 \    ATI 2016 Proxy Statement

Continuing Directors – Class I – Term to Expire at the 2018 Annual Meeting

ATI 2016 Proxy Statement    / 17

18 \    ATI 2016 Proxy Statement

Our Corporate Governance

We at ATI are committed to a strong self-governance program. Our corporate governance practices are designed to maintain high standards of oversight, compliance, integrity and ethics, while promoting growth in long-term stockholder value. The role of our Board of Directors is to ensure that ATI is managed for the long-term benefit of our stockholders and other stakeholders.

Each year we review our corporate governance and compensation policies and practices and engage with our stockholders. We compare our policies and practices to best practice models suggested by governance authorities, stockholders, or as shown by other public companies. In this way, we affirm our commitment to RELENTLESS INNOVATION™ by continually evolving our programs to benefit all of our stakeholders.

Our Commitment to Integrity

ATI is committed to conducting its business in an honest, ethical and lawful manner. Our employees strive to satisfy the spirit and intent, as well as the technical requirements, of the contracts we enter into and the laws, regulations and rules that govern us.

We are committed to protecting the health and safety of our employees, the environment, and our communities. We support sustainable development and work to constantly improve our operations to the benefit of our stockholders, employees, our customers and local communities.

We are committed to providing a workplace where employees are treated with dignity and respect, free of discrimination, and where all employees can fulfill their potential based on merit and ability.

We value our reputation. We pledge to promptly address issues in a lawful and proper manner. We strive to create value for our stakeholders while continually improving our performance as a good corporate citizen.

We are also committed to providing information in our financial reporting that is accurate, complete, objective, relevant, timely and transparent, and we have a robust system of internal controls.

We take these commitments seriously. Our management and Board of Directors have instilled a culture, throughout our organization, that supports and honors these commitments. We expect that the actions of our employees, officers and directors comply with these principles and all polices undertaken to further these objectives.

ATI 2016 Proxy Statement    / 19

Corporate Governance Guidelines

ATI’s Board of Directors has adopted Corporate Governance Guidelines, which are designed to assist the Board in the exercise of its duties and responsibilities to the Company. They reflect the Board’s commitment to monitor the effectiveness of decision making at the Board and management level with a view of achieving ATI’s strategic objectives. They are subject to modification by the Board at any time.

Corporate Guidelines for Business Conduct and Ethics

Our Corporate Guidelines for Business Conduct and Ethics (the “Code of Ethics”) applies to all directors, officers and employees, including our principal executive officer, our principal financial officer, and our controller and principal accounting officer. We require all directors, officers and employees to adhere to the Code of Ethics in addressing legal and ethical issues encountered in their work.

The Code of Ethics requires that our directors, officers and employees avoid conflicts of interest, comply with applicable laws, conduct business in an honest and ethical manner, and otherwise act with integrity and honesty in all of their actions by or on behalf of the Company. The Code of Ethics includes a financial code of ethics specifically for our Chief Executive Officer, our Chief Financial Officer, and all other financial officers and employees, which supplements the general principles in the Code of Ethics and is intended to promote honest and ethical conduct, full and accurate reporting, and compliance with laws as well as other matters.

Only the Audit Committee of the Board can amend or grant waivers from the provisions of the Code of Ethics relating to the Company’s executive officers and directors, and any such amendments or waivers will be promptly posted on our website at www.atimetals.com. To date, no such amendments have been made or waivers granted.

MANDATORY EMPLOYEE TRAINING

All employees are provided with a copy of the Code of Ethics. Each year, we require all officers and managers to certify as to their understanding of and compliance with the Code of Ethics. In addition, all directors, officers and other employees must annually complete an interactive online ethics course addressing the Code of Ethics. This course is part of ATI’s broader ethics and compliance program, which includes online ethics training that is administered by a third party. In 2015, online ethics courses were administered addressing the prevention of workplace violence, conflicts of interest, and anti-bribery/anti-corruption.

We encourage employees to communicate concerns before they become problems. We believe that building and maintaining trust, respect and communications between employees and management and between fellow employees is critical to the overriding goal of efficiently producing high quality products, providing the maximum level of customer satisfaction, and ultimately fueling profitability and growth.

The ATI Ethics Helpline provides confidential, secure, and anonymous reporting available 24 hours a day. Additionally, our Chief Compliance Officer and ethics officers at our operating companies also provide confidential resources for employees to surface their concerns without fear of reprisal.

ATI 2016 Proxy Statement    / 21

Investor Outreach and Stockholder Engagement

We value the input we receive from our stockholders. As part of our investor relations program, we regularly communicate with our investors and actively engage with them throughout the year. We solicit their feedback on corporate governance topics and ATI’s executive compensation program. Our goal is to be responsive to our stockholders and to ensure that we understand and address our stockholders’ concerns and observations. As a result of stockholder engagement, we have made significant changes to our corporate governance practices and executive compensation program over the past four years.

STOCKHOLDER ENGAGEMENT CYCLE

Our stockholder engagement usually begins following the Annual Meeting, when the Board considers the feedback received during the solicitation of proxies for the Annual Meeting. Management and the Board discuss topics of focus in the months that follow, which has included governance trends, regulatory developments, and our own policies and practices. During the fall, the Committee considers potential corporate governance or executive compensation changes in the context of further discussions with and feedback from stockholders. In the spring, we publish our annual communications to stockholders (our annual report and proxy statement) and solicit feedback from our investors about the significant topics to be addressed at our Annual Meeting. Following the Annual Meeting, the Board discusses vote outcomes and recommends follow-up actions. Throughout the year, management conducts regular meetings and discussions with investors.

22 \    ATI 2016 Proxy Statement

Board Information

BOARD COMPOSITION AND INDEPENDENCE

The Board of Directors determines the number of directors. The Board currently consists of eleven members:

The Board does not consider Richard J. Harshman, Chairman, President and Chief Executive Officer of ATI, to be independent. The Board, at its February 26, 2016 meeting, determined that the remaining ten current directors are independent in accordance with the NYSE listing standards, our company Board Independence Standards and the rules of the Securities and Exchange Commission (“SEC”).

In determining that these directors have no relationships with ATI other than as directors and stockholders of the Company, the Board examined certain business affiliations of Mr. Rohr and Mr. Morehouse.

James E. Rohr currently serves on the board of directors of General Electric Company (“General Electric”). During 2015, the Company supplied General Electric with nickel-based superalloys and jet engine disc-quality mill products under an ongoing commercial relationship between the Company and General Electric. The amounts paid to the Company by General Electric in 2015 represent a de minimis portion of the revenues of General Electric, and the compensation received by Mr. Rohr from General Electric for his service as a director is not affected by the ongoing commercial relationship between the Company and General Electric. The Board has determined that the transactions between the Company and General Electric:

The Board determined that Mr. Rohr is an independent director under NYSE existing guidelines and the Company’s categorical Board independence standards.

David J. Morehouse is the Chief Executive Officer and President of Pittsburgh Penguins LLC, which owns and operates the Pittsburgh Penguins National Hockey League team, and Pittsburgh Arena Operating LLC (collectively, the “Entities”) and other affiliated entities. ATI is a party to a sponsorship agreement with Pittsburgh Penguins LLC, under which the Company pays an annual fee to Pittsburgh Penguins LLC in exchange for sponsorship opportunities associated with the Pittsburgh Penguins National Hockey League franchise. The sponsorship agreement expires in June 2016. ATI is party to an arena executive suite license agreement that expires in June 2017 (the “License Agreement” and with the Sponsorship Agreement, the “Agreements”) with an entity that is affiliated with Pittsburgh Arena Operating LLC. The Agreements will not be renewed after expiration. The annual fees paid by ATI to the Entities represents a de minimis portion of both ATI’s revenues and the revenues of the Entities, and, therefore, all amounts were substantially less than the thresholds set in the NYSE’s listing standards which disqualify a director from being independent.

Mr. Morehouse’s compensation from the Entities is not affected by the fees that the company pays under these Agreements. The Board has determined that the transactions between the Company and the Entities:

ATI 2016 Proxy Statement    / 23

The Board determined that Mr. Morehouse is qualified as an independent director under NYSE existing guidelines and the Company’s categorical Board independence standards.

BOARD LEADERSHIP

The Board of Directors has the flexibility to determine whether it is in the best interests of ATI and its stockholders to separate or combine the roles of Chairman and Chief Executive Officer at any given time. Whenever a Chairman and/or Chief Executive Officer is appointed, or at such other times as it deems appropriate, the Board of Directors assesses whether the roles should be separated or combined based upon its evaluation of, among other things, the existing composition of the Board of Directors and the circumstances at the time. The Board has considered the roles and responsibilities of the Chairman and the Chief Executive Officer, and, while it retains the discretion to separate the roles in the future as it deems appropriate and acknowledges that there is no single best organizational model that is most effective in all circumstances, the Board currently believes that the Company and its stockholders are best served by having Mr. Harshman serve concurrently as Chairman and Chief Executive Officer. The Board of Directors believes that Mr. Harshman’s service in both capacities promotes unified leadership and direction for the Company and allows for a single, clear focus on the efficient implementation of ATI’s strategies to maximize stockholder value over the long-term. In addition, the Board of Directors believes that Mr. Harshman, serving in both capacities, has been an effective bridge between the Board and ATI’s management.

The Board of Directors believes that this leadership structure is appropriate for ATI and in the best interests of our stockholders at this time. Through governance features such as the establishment of a Lead Independent Director position, the appointment of only independent directors to the standing committees of the Board of Directors, and regular use of executive sessions of the independent directors, the Board is able to maintain appropriate independent oversight of our business strategies and activities.

24 \    ATI 2016 Proxy Statement

These governance features have been effective in promoting a full and free discussion and analysis at the Board level of issues important to the company. At the same time, the Board of Directors is able to take advantage of the blend of leadership, experience and extensive knowledge of ATI, our industry and the markets in which we compete that Mr. Harshman brings to the combined roles of Chairman and Chief Executive Officer.

BOARD AND COMMITTEE MEMBERSHIP – DIRECTOR ATTENDANCE AT MEETINGS

During 2015, the Board of Directors held seven meetings, including one strategy retreat. In 2015, directors attended over 97% of all Board meetings and meetings of Board committees of which they were members.

The independent, non-management directors meet separately in regularly scheduled executive sessions without members of management (except to the extent that the non-management directors request the attendance of a member of management). The Lead Independent Director presides over meetings of the independent directors.

A Board meeting is typically scheduled in conjunction with our annual meeting of stockholders and it is expected that our directors will attend absent good reason. In 2015, all directors attended our annual meeting of stockholders.

The table below provides information with respect to current Board committee memberships of the non-employee directors. The table also sets forth the number of meetings held by each Board committee in 2015.

BOARD COMMITTEES

The Board of Directors has five standing committees: Audit Committee, Finance Committee, Nominating and Governance Committee, Personnel and Compensation Committee, and Technology Committee. All of the standing committees of the Board of Directors are comprised entirely of independent directors.

Each committee has a written charter that describes its responsibilities. Each of the Audit Committee, the Nominating and Governance Committee and the Personnel and Compensation Committee has the authority, as it deems appropriate, to independently engage outside legal, accounting or other advisors or consultants. In addition, each committee annually conducts a review and evaluation of its performance and reviews and reassesses its charter.

ATI 2016 Proxy Statement    / 25

26 \    ATI 2016 Proxy Statement

ATI 2016 Proxy Statement    / 27

BOARD’S ROLE IN RISK OVERSIGHT

The Board of Directors as a whole actively oversees the risk management of the Company. Enterprise risks—the specific financial, operational, business and strategic risks that the Company faces, whether internal or external—are identified and prioritized by the Board and management together, and then each specific risk is assigned to the full Board or a Board committee for oversight.

Board/Committee Primary Areas of Risk Oversight

Management regularly reports to the Board or the relevant Committee on actions that the Company is taking to manage these risks. The Board and management periodically review, evaluate and assess the risks relevant to the company.

28 \    ATI 2016 Proxy Statement

Director Compensation

BOARD OF DIRECTORS’ ROLE AND COMPENSATION

Non-employee directors receive compensation for their service, which is designed to fairly compensate them for their board responsibilities and align their interests with our stockholders. The Nominating and Governance Committee periodically reviews and evaluates the non-employee director compensation program to ensure that it is competitive with ATI’s industry peers and best practices and serves the purposes of attracting and retaining high quality directors. The Nominating and Governance Committee uses an independent consultant, Pay Governance LLC, which is the same consultant retained by the Personnel and Compensation Committee, to provide market and comparison data and information on current developments and practices in director compensation. ATI’s non-employee director compensation program is competitive and market-based.

DIRECTOR STOCK OWNERSHIP GUIDELINES

The Board encourages directors to obtain a meaningful stock ownership interest in ATI. Under the stock ownership guidelines applicable to all non-employee directors, each non-employee director is expected to own at least 10,000 shares of ATI Common Stock within five years of his or her initial election to the Board. Furthermore, directors are required to retain one-third of any awarded stock until compliance with the guidelines is achieved. Each of the directors was in compliance with the guidelines as of December 31, 2015 or is reasonably proceeding with compliance as of the applicable five-year anniversary of his or her initial election to the Board.

ATI 2016 Proxy Statement    / 29

Elements of Director Compensation

2015 Changes to Director Compensation

In December 2014, the Board approved certain changes to the Company’s non-employee director compensation program beginning in 2015 based on a competitive market analysis performed by the compensation consultant; the result is the program reflected in the above table. These changes more accurately represent the amounts paid in the U.S. market for board membership and aligns ATI director compensation with peer group practices.

Other

In 2004, the Board froze and discontinued the Company’s Fee Continuation Plan for Non-Employee Directors. Under the frozen plan, an amount equal to the annual retainer fee in effect for 2004 (which was $28,000) will be paid annually to the members of the Board as of December 31, 2004, following the termination of the director’s service as a Board member. The fee will be paid for each year of the director’s credited service as a director (as defined in the Plan) up to a maximum of ten years.

2015 Non-Employee Director Compensation

Non-employee directors are not granted option awards or non-equity incentive plan compensation awards, and do not have company pensions and non-qualified deferred compensation earnings.

30 \    ATI 2016 Proxy Statement

Item 2 — Approval of Amendments to the Certificate of Incorporation to Declassify the Board of Directors

We are asking our stockholders to approve these amendments to declassify our Board of Directors. This proposal provides for a phased-in declassification of the Board and requires each director nominee in the future to be elected annually for a one-year term.

Background

Our Certificate of Incorporation currently divides the Board of Directors into three classes. Each class is elected for three-year terms, with the terms staggered so that approximately one-third of our directors, plus any newly appointed directors, stand for election each year. There are currently four Class II directors with terms expiring at the 2016 Annual Meeting of Stockholders, four Class III directors with terms expiring at the 2017 Annual Meeting of Stockholders and three Class I directors with terms expiring at the 2018 Annual Meeting of Stockholders. The Board of Directors recommends at this time certain amendments to our Certificate of Incorporation that would provide for a phased-in declassification of the Board of Directors and require each director nominee in the future to be elected annually for a one-year term. If this proposal is approved by our stockholders, the Board of Directors also will approve certain conforming amendments to our bylaws. The text of the proposed Certificate of Amendment to the Company’s Certificate of Incorporation is attached as Appendix A to this proxy statement.

Proposed Declassification Amendment

Under the proposed amendments to our Certificate of Incorporation, the declassification of the Board of Directors would be phased in over a three-year period. In accordance with Delaware corporate law, declassification would not result in the curtailment of any incumbent director’s term of office prior to the expiration of that term.

Until the Board of Directors is fully declassified, any director appointed to the Board of Directors to fill a vacancy will hold office until the next election of the class for which the director is chosen. Following the full declassification of the Board of Directors, any director appointed to the Board of Directors to fill a vacancy will hold office until the next annual meeting of stockholders and until his or her successor is duly elected and qualified or until his or her earlier resignation or removal.

Delaware corporate law provides that the members of a classified board of directors may be removed only for cause. Accordingly, our Certificate of Incorporation currently provides that all of our directors are removable only for cause. If this proposal is approved, a member of our Board of Directors may be removed with or without cause once he or she is elected to a one-year term.

ATI 2016 Proxy Statement    / 31

This description of the proposed amendments to the Company’s Certificate of Incorporation is qualified in its entirety by reference to the full text of the proposed Certificate of Amendment to our Certificate of Incorporation, a copy of which is attached as Appendix A.

Rationale for Declassification of the Board of Directors

In the past, our Nominating and Governance Committee and our Board of Directors as a whole have believed that a classified board structure served the best interests of the Company and its stockholders. A classified board generally provides for board continuity and stability and promotes the ability of the board to focus on the long-term strategies and interests of ATI and the creation of stockholder value. In addition, a classified board structure can assist in attracting and retaining committed directors who are able to develop a deeper knowledge of a company’s business and the environment in which it operates.

With continuing evaluations of trends and developments in corporate governance, the Nominating and Governance Committee and the Board of Directors as a whole have reviewed their respective positions on classified boards. While they continue to recognize the potential benefits of classified boards, they also are committed to ensuring maximum accountability to our stockholders. They believe that the declassification of our Board of Directors would provide stockholders with an additional opportunity to register their views at each annual meeting, as well as through ongoing stockholder engagement. As a result, the Nominating and Governance Committee recommended to the Board of Directors that a proposal to declassify the Board of Directors be submitted to the Company’s stockholders at the 2014 Annual Meeting of Stockholders, and the Board of Directors unanimously approved the recommendation. However, the declassification proposal did not receive the requisite support of stockholders at the 2014 Annual Meeting of Stockholders in order to be enacted.

Although the Board’s prior attempt to implement a declassification of the board did not receive enough votes to pass, the Nominating and Governance Committee and the Board of Directors continued to evaluate trends and developments in corporate governance, including consideration of stockholder perspectives and the Board’s ongoing continued commitment to accountability and responsiveness. By unanimous recommendation of such committee and unanimous approval of the Board, the Board of Directors has determined to submit to the Company’s stockholders at the 2016 Annual Meeting of Stockholders this proposal to declassify the Board of Directors and recommend that stockholders vote FOR approval of the declassification amendments.

Legal Effectiveness

If it is approved by the requisite favorable vote of our stockholders, this proposal will become effective upon the filing of a Certificate of Amendment to our Certificate of Incorporation with the office of the Secretary of State of the State of Delaware. We intend to make this filing promptly after the 2016 Annual Meeting of Stockholders if this proposal is approved. If this proposal does not receive the required number of votes in favor of it, then our Certificate of Incorporation will not be amended and our Board of Directors will remain classified with all of our directors continuing to serve three-year terms in accordance with the current provisions of our Certificate of Incorporation. If stockholders vote to approve this proposal, then the Board of Directors will also approve certain conforming amendments to our bylaws.

Required Stockholder Approval

Our Certificate of Incorporation provides that the affirmative vote of the holders of at least 75% of the combined voting power of all outstanding voting securities of the Company entitled to vote generally in the election of directors, voting together as a single class, is required to amend the portions of the Certificate of Incorporation that are the subject of this

32 \    ATI 2016 Proxy Statement

proposal. Abstentions and broker non-votes will have the same effect as votes against this proposal. Under Delaware law, any amendment of ATI’s Certificate of Incorporation must be approved by ATI’s stockholders. Any amendment of ATI’s Certificate of Incorporation, including to revise required stockholder approval levels, must be approved by the affirmative vote of the holders of at least 75% of the shares of ATI Common Stock outstanding and entitled to vote.

Related Party Transactions

The Board of Directors has adopted a written Statement of Policy with respect to Related Party Transactions. The Policy applies to transactions or arrangements between ATI and a related person (namely directors, executive officers, and their immediate family members, and 5% stockholders) with a direct or indirect material interest in the transaction, including transactions requiring disclosure under Item 404(a) of Regulation S-K.

Under the Policy, no related party transaction may occur unless it is approved or ratified by the Audit Committee or approved by the disinterested members of the Board of Directors. The Audit Committee is primarily responsible for approving and ratifying related party transactions, and in doing so, will consider all matters it deems appropriate, including the dollar value of the proposed transaction, the relative benefits to be obtained and obligations to be incurred by the Company, and whether the terms of the transaction are comparable to those available to third parties.

Compensation Committee Interlocks and Insider Participation

No member of the Personnel and Compensation Committee is an officer or employee of the Company, and no member of the Committee has a current or prior relationship, and no officer who is a statutory insider of the Company has a relationship, to any other company, required to be described under the Securities and Exchange Commission rules relating to disclosure of executive compensation.

Stock Ownership Information

Section 16(a) Beneficial Ownership Reporting Compliance

The rules of the SEC require the Company to disclose late filings of reports of stock ownership (and changes in stock ownership) by its directors and statutory insiders and by persons who beneficially own more than ten percent of a registered class of the Company’s equity securities. Based upon a review of filings with the SEC and written representations, the Company believes that, in 2015, all such persons complied with the reporting requirements of Section 16(a) of the Securities Exchange Act of 1934 on a timely basis.

ATI 2016 Proxy Statement    / 33

Five Percent Owners of Common Stock

The entities listed in the following table are beneficial owners of five percent or more of ATI Common Stock as of December 31, 2015, based on information filed with the SEC. In general, “beneficial ownership” includes those shares a person has the power to vote or transfer, and options to acquire Common Stock that are exercisable currently or within 60 days.

34 \    ATI 2016 Proxy Statement

Stock Ownership of Directors, Board Nominees and Executive Management

The following table shows the shares of Common Stock reported to ATI as beneficially owned as of March 1, 2016 by the nominees for director, the continuing directors, each officer named in the Summary Compensation Table, and for all directors, officers and other statutory insiders as a group. Unless indicated otherwise below, the information provided in the following table is based on the Company’s records, information filed with the SEC, and information furnished by the respective individuals.

For biographical information regarding the beneficial owners, please see information under “Item 1—Election of Directors” and “Members of ATI’s Management Executive Council” of this proxy statement. The business address for each beneficial owner is c/o Allegheny Technologies Incorporated, 1000 Six PPG Place, Pittsburgh, PA 15222.