ATI INC

This summary highlights information that is contained elsewhere in this Proxy Statement. You should carefully read this Proxy Statement in its entirety before voting, as this summary does not contain all of the information that you should consider.

ANNUAL MEETING OF STOCKHOLDERS

MEETING AGENDA AND VOTING MATTERS

DIRECTOR NOMINEES – CLASS I – TERM TO EXPIRE IN 2027

WHAT’S NEW

Among many recent achievements and changes driving further growth, value creation and shareholder return, this Proxy Statement reflects: ◆ Kimberly A. Fields will lead ATI as President and CEO beginning this July, with Mr. Wetherbee becoming Executive Chairman ◆ Ms. Fields and Ruby Sharma were appointed to our Board, expanding representation of women on our Board to 36% ◆ Vaishali Bhatia joined our executive leadership as Senior Vice President, General Counsel and Chief Compliance Officer ◆ We dramatically reduced our exposure to pension volatility risk, bringing further stability and strength to our balance sheet whilecontinuing to fully meet our obligations to pension participants ◆ Our relative Total Shareholder Return continued to significantly outpace the S&P 500; we returned $85 million to shareholders through our share repurchase program and announced a new $150 million program

BOARD COMPOSITION

ATI has a diverse, highly credentialed and highly experienced Board. Our directors possess a variety of tenure, qualifications, backgrounds, skills and experiences contributing to a Board that is well-rounded and well-positioned to effectively oversee our business and promote the interests of our stakeholders.

Highly Engaged Board Guides the Strategic Direction of Our Company

Focused and Thoughtful Board Refreshment

GOVERNANCE HIGHLIGHTS

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

RISK OVERSIGHT SUMMARY

Understanding the risks and opportunities facing the Company is fundamental to the Board’s ability to effectively exercise its oversight function and promote stakeholder interests. We view the consideration of enterprise risk—the specific financial, operational, business and strategic risks that the Company faces—as integral to our decision-making processes at both the Board and management level. The following, which is meant to be read in conjunction with the more detailed discussion of risk management and oversight beginning on page 22 of this Proxy Statement, illustrates the roles of our Board, its Committees and our management play in the oversight and mitigation of enterprise-wide risks.

Cybersecurity Risk. Our Board is actively engaged in the oversight of our cybersecurity and information security programs. Our Chief Information Security Officer oversees our comprehensive cybersecurity program, and as part of its program of regular oversight, the Audit and Risk Committee receives quarterly reports from our Chief Digital and Information Officer on ATI’s cybersecurity risk profile and enterprise cybersecurity program. For more information, see “Cybersecurity Risk Management and Oversight” on page 23. Risks Associated with Climate Change. The Board’s Audit and Risk Committee oversees risks associated with climate change and other environmental compliance and sustainability matters, with additional oversight from the Technology Committee. For more information, see “Corporate Responsibility Risk Oversight” on page 24.

2023 BUSINESS PERFORMANCE

ATI continued its strong performance trajectory in 2023. With our focused commitment to doing what we say we are going to do and solving our customers’ most difficult challenges, we created opportunities in the face of the ongoing global geopolitical, supply chain and other challenges that continue to impact our current environment, capturing new market share and sharpening our operation advantage to drive shareholder value. We continued to successfully execute our strategy, working to ensure sustainable growth as we capitalize on the opportunities presented by unprecedented demand growth, particularly in our core aerospace and defense markets.

Sales of $4.2 billion compared to $3.8 billion in 2022

Gross profit of $803 million compared to $714 million in 2022.

Net income of $423 million, compared to $339 million in 2022

Preserved strong liquidity and cash position

Returning capital to stockholders.

We believe that the strategic and operational changes we have achieved in recent years and continue to pursue are positioning our business for success in 2024 and beyond, and critically, are driving our ability create shareholder value. The following illustrate ATI’s relative total shareholder return (“TSR”) compared to the S&P 500 in 2023 and since the beginning of 2022:

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 a variety of topics, including among others, matters of corporate responsibility, corporate governance and ATI’s executive compensation program. Our goal is to be responsive to our stockholders and to ensure that we understand and address their concerns and observations. For a more detailed discussion of our long-standing and robust annual engagement effort, see page 35 of this Proxy Statement.

As a result of our stockholder engagement, we have: sharpened our corporate responsibility and corporate governance reporting in general; expanded our disclosures regarding risk oversight, including as it pertains to cybersecurity; significantly expanded our reporting of the potential impacts of climate change on our business with the publication of our stand-alone TCFD Report; made significant changes to our corporate governance practices in recent years; and made responsive changes to our executive compensation programs.

2023 Say On Pay Vote

Last year, following extensive shareholder engagement in 2022 and responsive changes to certain aspects of our executive compensation programs, our Say on Pay proposal received the support of more than 99% of the shares voted at our 2023 Annual Meeting. Our Board believes that this outstanding support from our stockholders is a result of our robust and responsive program of engagement and our continuing commitment to ensure a strong link between pay and performance.

OUR COMPENSATION PHILOSOPHY—PAY FOR PERFORMANCE

ATI’s executive compensation program is designed to support our long-term strategic vision and to align with ourpay-for-performance philosophy. The goals of our program are to compensate executive management based on performance, create long-term stockholder value and attract and retain key employees. Paying for performance is a key attribute of ATI’s compensation philosophy. As such, a significant portion of the compensation of each named executive officer (“NEO”) is subject to the achievement of rigorous performance goals and, therefore, is “at risk.”

2023 Target Pay Mix

TOTAL REALIZED COMPENSATION

When making determinations and awards under our incentive plans, the Compensation and Leadership Development 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.

The comparison of 2023 target compensation to realized compensation for our NEOs reflects continuing improvement in our business and the outcome of our long-term and short-term incentive programs. Notably, we established short-term incentive targets for 2023 that, consistent with our expectations for the performance of our business, were significantly more challenging than our 2022 short-term incentive targets, resulting in short-term incentive payouts that, while above target, were lower than those paid for 2022. At the same time, our total shareholder return, which generally has significantly outpaced that of our peers for the last two years, reflects the success of our multi-year strategies and resulted in a near-maximum (198.5%) payout for our 2021-2023 PSUs. For earlier performance periods illustrated below, the outcome of our long-term incentive programs was negatively impacted to a meaningful degree by the impact of the COVID-19 pandemic and other challenges that unexpectedly confronted our business in 2020 and 2021.

2017-2023 Total Realized Compensation as % of Annual Target

These multi-year trends demonstrate our ongoing commitment to compensating our leadership based on the Company’s performance and placing a significant portion of senior executive compensation “at risk.”

2023 Target Annual Compensation Comparison to Total Realized Compensation

Total Realized Compensation is calculated as follows: