Our Board re-evaluates our leadership structure on an ongoing basis and may change it as circumstances warrant. At present, David S. Graziosi, our President and Chief Executive Officer, or CEO, serves as ChairmanChair of the Board. Because Mr. Graziosi is not independent, our Board designated Thomas W. Rabaut to continue to serve as Lead Independent Director until his current term ends at the Annual Meeting. Following the Annual Meeting, the Board has designated Richard P. Lavin to assume the role ofserve as our Lead Independent Director. In such position, the Lead Independent Director serves as chairmanchair of executive sessions of the independent directors, calls meetings of the independent directors and communicates the results of such meetings to the ChairmanChair of the Board, facilitates communication and serves as a liaison between the independent directors and the ChairmanChair of the Board and between the independent directors and management, reviews and approves, in connection with the ChairmanChair of the Board, all agendas for meetings of the Board and communicates with major stockholders upon request. Our Board believes that Mr. Graziosi filling the role of ChairmanChair of the Board, while also having a Lead Independent Director with the powers and responsibilities outlined above, is an appropriate and efficient leadership structure. Our Board re-evaluates our leadership structure on an ongoing basis and may change it as circumstances warrant.

While risk management is primarily the responsibility of our management, our Board provides overall risk oversight, focusing on the most significant risks facing us. Our Board oversees the risk management processes that have been designed and are implemented by our executives to determine whether those processes are functioning as intended and are consistent with our business and strategy. Our Board executes its oversight responsibility for risk management directly and through its committees. Our Board’s roleIn addition, our Lead Independent Director aids in riskthe independent oversight has not affected its leadership structure.of management.

The Audit Committee is specifically tasked with overseeing our compliance with legal, ethical and regulatory requirements, oversight of climate-related and cybersecurity risks, discussing our major financial risk exposures, including our risk assessment and risk management processes, with management and receiving information on material legal and regulatory affairs. Our Executive Director, FinancialGlobal Finance and Tax Reporting coordinates our enterprise risk management process, and the Audit Committee and full Board receive regular reports regarding our enterprise risk

management process. The Compensation Committee is tasked with overseeing our compensation-related risk assessment. See “Executive Compensation—Compensation-Related Risk Assessment” below. Our Board’s other committees oversee risks associated with their respective areas of responsibility.

The full Board considers specific risk topics, including risk-related issues pertaining to laws and regulations enforced by United States and foreign government regulators, risks associated with our business plan, strategy and capital structure, risks related to the competitive market in which we operate, and risks related to interruption of our business due to natural disasters, power outages, labor strikes and public health crises such as pandemics and epidemics or the like. In addition, our Board receives reports from members of our management that include discussions of the risks and exposures involved with their respective areas of responsibility. Further, our Board is routinely informed of developments that could affect our risk profile or other aspects of our business.

The following chart highlights the specific skills, knowledge and experience of each of our current directors who are nominated for reelection at the Annual Meeting. A lack of a mark does not mean the director nominee does not possess that qualification or skill; rather, a mark indicates a specific area of focus or expertise on which our Board relies most heavily. Each director nominee’s biography describes these qualifications and relevant experience in more detail.

In August 2022, the Nominating and Corporate Governance Committee charter require diverse candidates to be considered in each search for new Board nominees. Our Board recommends candidates based on the diversity of their business or professional experience, background, talentsrecommended, and perspectives. Our Board considers diversity in the context of the Board as a wholeapproved and takes into accountappointed four new directors to the personal characteristics, such as gender, race/ethnicity, age, experience,Board, including financial expertise,one director who added racial/ethnic diversity to the Board.

In addition, the chair of our Audit Committee is ethnically diverse and educationalthe chairs of our Compensation Committee and professional background, of current and prospective directors. Our Board believes this process will best facilitate Board deliberations that reflect a broad range of perspectives and leadour Finance Committee are female, further demonstrating our Board’s commitment to a more effective decision-making process.diversity.

In 2022, we added five new directors to our Board – Messrs. Barbour, Christman, Ostojic and Shivram and General Perna. In addition, as discussed above, four of our longer-tenured directors are not standing for reelection at the Annual Meeting. The following table summarizes certain self-identified characteristics of our ten directors who are standing for reelection at the Annual Meeting.

Our Board has implemented a process whereby our stockholders and all interested parties may send communications to our Board’s attention. Any stockholder or interested party desiring to communicate with our Board, or one or more specified members thereof, should communicate (i) in writing addressed to Allison Transmission Holdings, Inc., Board of Directors, Attention: Secretary, One Allison Way, Indianapolis, Indiana 46222, (ii) via email at stockholders@allisontransmission.com or (iii) via telephone at (317) 242-4425. Our Board has instructed our Secretary to promptly forward all such communications to the specified addressees thereof. With respect to correspondence received by the Company that is addressed to one or more directors, the Board has requested that the following items not be distributed to directors because they generally fall into the purview of management, rather than the Board: junk mail and mass mailings, service complaints and inquiries, resumés and other forms of job inquiries, solicitations for charitable donations, surveys, business solicitations and advertisements.

We utilize ISO 14001 processes and procedures to manage our environmental management system. Every year since 2008,2009, we have achieved “landfill-free” certification while also decreasing energy and water usage at our global headquarters and manufacturing operations in Indianapolis.Indianapolis and have updated our facilities with more energy-efficient equipment. In addition, we have also implemented programs to reduce energy and water usage at our Lewisburg, Tennessee, Szentgotthárd, Hungary and Chennai, India manufacturing facilities.

Our overriding priority is to protect the health and safety of each employee. As part of our health and safety programs, employeesAllison is certified in ISO 45001, Occupational Health and Safety Management Systems. ISO 45001 is the only internationally recognized Safety Management System. Employees participate in training focused on this topichealth and safety and metrics are reviewed regularly, including the number of injury incidents that occur and those incidents that result in lost work days. For 2022,2023, we achieved an overall recordable rate of 2.26,1.64 at our global locations, meaning that for every 100 employees, 2.261.64 employees incurred an injury that resulted in recordable medical treatment and the number of lost work days was 0.87,0.63 at our global locations, meaning that for every 100 employees, 0.870.63 individuals experienced an incident that resulted in days away from work.

As the people behind the product, we seek to hold ourselves to the highest ethical standards in everything that we do. Quality solutions come from quality people, and integrity is crucial. The Allison Code of Business Conduct emphasizes the importance of driving integrity worldwide by focusing on five pillars: personal integrity, integrity in the workplace, integrity in the marketplace, integrity in our societies and communities and integrity toward the environment. The Code of Business Conduct applies to all of our employees, officers and directors. The Code of Business Conduct includes expectations regarding issues such as fair treatment and non-discrimination, health and safety, anti-corruption, fair competition, insider trading, environmental protection and child labor and modern slavery. All of our global salaried employees participate in an annual training on the Code of Business Conduct.

Our Supplier Code of Conduct requires our suppliers to act consistently with Allison’sour approach to integrity, responsible sourcing and supply chain management. The Supplier Code of Conduct addresses, among other things, human rights, health and safety, the environment and business integrity.

The membership of the Audit Committee, Compensation Committee, Finance Committee and Nominating and Corporate Governance Committee is composed entirely of independent directors and meets the heightened standards of independence for audit committee and compensation committee members, respectively, required by Securities and Exchange Commission, or SEC, rules and the NYSE Manual.

The Audit Committee oversees our accounting and financial reporting processes and the audits of our consolidated financial statements provided by us to any governmental body or the public and prepares the report of the Audit Committee included under “Report of the Audit Committee” in this proxy statement. The Audit Committee also assists our Board in discharging its oversight responsibilities regarding the integrity of our consolidated financial statements, our compliance with legal, ethical and regulatory requirements, oversight of climate-related and cybersecurity risks, the qualifications and independence of our independent registered public accounting firm and the performance of our internal audit function. The Audit Committee has sole authority to appoint, subject to stockholder ratification, or replace our independent registered public accounting firm and pre-approves the auditing services and permitted non-audit services to be performed by our independent registered public accounting firm, including the fees and terms thereof. The Audit Committee reviews and discusses with management and our independent registered public accounting firm our annual audited consolidated financial statements, our quarterly earnings releases and financial statements and significant financial reporting issues and judgments made in connection with the preparation of our financial statements. The charter of the Audit Committee requires that each member meet the independence and experience requirements of the NYSE, the Securities Exchange Act of 1934, as amended, or the Exchange Act, and the rules and regulations of the SEC.

Our Board has determined that Alvaro Garcia-Tunon and Krishna Shivram each qualifies as an “audit committee financial expert” as defined by SEC rules.

The Compensation Committee (i) reviews, approves and/or oversees compensation provided to our executive officers and employees and all agreements and arrangements with respect thereto, (ii) establishes our general compensation policies and (iii) reviews, approves and/or oversees the administration of our employee benefits plans and makes recommendations for stockholder approval of such plans, as applicable.

The Compensation Committee may take into consideration the recommendations of our CEO with respect to the compensation of our other executive officers. The Compensation Committee also discusses with management the Compensation Discussion and Analysis, and, if appropriate, recommends its inclusion in our annual report on Form 10-K and proxy statement and issues the report on its activities which appears under “Executive Compensation—Compensation Committee Report” in this proxy statement. The charter of the Compensation Committee requires that each member meet the independence requirements of the NYSE, the Exchange Act and the rules and regulations of the SEC.

The Compensation Committee has authority to retain the advice and assistance of independent counsel, compensation consultants or other experts or consultants. For 2022,2023, the Compensation Committee retained

The charter of the Nominating and Corporate Governance Committee requires that all responsibilities of such committee required under NYSE rules to be performed by directors who satisfy the independence requirements of the NYSE be performed solely by the members of such committee who qualify as independent.

The Finance Committee assists our Board in discharging our Board’s responsibilities regarding significant transactions, including strategic investments, mergers and acquisitions and divestitures, capital expenditures, capital structure, including dividends, stock repurchases and borrowing and equity practices and other financial strategies and special projects. The Finance Committee has the authority to retain its own independent counsel, experts or advisors.

Our Compensation Committee consisted of General Reynolds, Messrs. Askren, Barbour, Christman and Lavin and Ms. Altmaier from January 20222023 through August 2022,May 2023, and has consisted of General Reynolds, Messrs. Askren, Barbour, Christman and Lavin and Ms. Altmaier since August 2022.May 2023. None of the members of our Compensation Committee during 20222023 or as of the date of this proxy statement is or has been one of our officers or employees. During fiscal year 2022,2023, none of our executive officers served as a member of the board of directors or compensation committee, or other committee serving an equivalent function, of any entity that has one or more executive officers who serve as members of our Board or our Compensation Committee.

Except as otherwise indicated in these footnotes, each of the directors and executive officers listed has, to our knowledge, sole voting and investment power with respect to the shares of common stock. None of the shares owned by our directors, nominees for director and executive officers have been pledged as security.

Section 16(a) of the Exchange Act requires our officers and directors and persons who own more than 10% of our common stock to file reports of ownership and changes in ownership with the SEC. Based solely on our review of such filings and written information given to us by our directors and executive officers, we believe that all such reports required by Section 16(a) of the Exchange Act were in compliance with such filing requirements during the year ended December 31, 2022, except for one report2023. However, the Form 3 filed on behalf of Rafael BassoThomas Eifert on December 2, 2022 reporting the vestingAugust 6, 2021 inadvertently understated Mr. Eifert’s direct holdings as of RSUs and dividend equivalents on October 1, 2022, and one report filed on behalf of Ryan Milburn on February 14, 2023 reporting a stock option exercise and subsequent sale of the underlyingsuch date by 3,906 shares on November 17, 2022, which reports were inadvertently filed late due to administrative error.error, which was corrected in a Form 3/A filed on March 12, 2024.

Mr. Coll joined Allison as Senior Vice President, Global Marketing, Sales and Service in October 2016. Prior to joining Allison, Mr. Coll was Vice Present of Sales and Marketing at Gerdau Ameristeel U.S., a manufacturer of steel products, from January 2015 to October 2016. Prior to that, Mr. Coll served fourteen years at Eaton Corporation, or Eaton, most recently as Vice President of Global Marketing for the vehicle group from January 2011 to January 2015. Prior to that, he held a number of other roles at Eaton, including Director of Global Channel Marketing for Eaton Electrical, General Manager of Aftermarket and Vehicle Solutions for Truck Components and Vice President of Sales and Marketing for Truck Components. Prior to joining Eaton, Mr. Coll served thirteen years at Philips Electronics in a variety of sales and distributor relations roles.Electronics. Mr. Coll earned a bachelor’s degree in business administration from West Virginia University and a Master of Business Administration from the University of Pittsburgh. Mr. Coll serves as currenta Vice Chairman of the Heavy Duty Manufacturers Association’s Heavy Duty Business Forum and is a member of its Board of Governors. He also serves as a Boardboard member of the Motor & Equipment Manufacturers AssociationAssociation. He also serves as well asa board member of the Truck Renting & Leasing Association.

Mr. Eifert currently serves as Vice President, Quality, Planning and Program Management, a position he has held since December 2021. In August 2021, following leadership changes, his role began reporting directly to the CEO. In August 2020, his role was expanded to include oversight of Quality and Reliability and Engineering Test Operations including our Vehicle Electrification and Environmental Test Center. Mr. Eifert previously held the positions of Vice President, Program Management and Product Planning from December 2018 until December 2021, where he was responsible for planning and leading product initiatives across the portfolio serving the On-Highway, Off-Highway and Defense end markets, Vice President, Program Management and Mobile Source Emissions from April 2017 until December 2018, and Executive Director, Product Teams and Program Management from 2014 until April 2017.

Mr. Eifert began his career with General Motors in 1989 as a co-op student at the Inland (Fisher Guide) Division in Dayton, Ohio and served in a variety of roles with Delphi Automotive. He joined Allison in 1996 as a Supplier Quality Engineer. In 1997, he was promoted to Senior Supplier Quality Engineer and in 1999 to Supervisor, Supplier Quality Engineering. Over the course of his career, he worked in several different areas of the business, including Purchasing, Business Planning and Engineering. In 2007, he was promoted to Executive Director of Global Customer Support in the Marketing, Sales and Service group. In 2013, he rejoined the Engineering division and then assumed a cross-functional leadership role to define, plan and implement product initiatives for the On-Highway Products Team, the Controls System Team and the Off-Highway Products Team. Mr. Eifert is also the executive sponsor for the Company's multicultural Employee Resource group. He graduated from the University of Dayton with a degree in mechanical engineering and earned a Master in Business Administration from Butler University.

Mr. Milburn currently serves as Vice President, Product Engineering and Technology Development (previously Vice President, Product Engineering) for Allison, Transmission, a position he has held since August 2021. Mr. Milburn previously served as Vice President, e-Mobility Engineering from May 2020 until August 2021. Prior to that, he served as Vice President, Mechatronics & Controls Software from May 2019 until June 2020, and before that as Executive Director, Embedded Controls Systems from July 2015 until May 2019. Prior to his positions in engineering leadership, Mr. Milburn served as Managing Director Europe, Middle East and Africa (EMEA) based in The Netherlands from 2012 to 2015 and as Vice President and Chief Information Officer following our divestiture from General Motors in 2007. Mr. Milburn began his career with Allison in 1990, holding roles of increasing responsibility in manufacturing operations and information technology including Manager of Information & Control Systems for the green-field launch of our former manufacturing facility in Baltimore, Maryland, Manager of Engineering & Product Development Systems and Chief Information Officer. Mr. Milburn received his Bachelor of Science degree in Electrical Engineering and Computer Science from GMI Engineering & Management Institute as part of a co-operative education program with Allison. Mr. Milburn serves on the Marian University E.S. Witchger School of Engineering Board of Visitors and SAE International COMVEC^TM Executive Council.

Mr. Pittard joined Allison in October 2015 as Deputy Vice President of Defense Programs. He was promoted to Vice President, Defense Programs in January 2016. Mr. Pittard retired from the U.S. Army with the grade of Major General (2 Star) after 34 years of active duty. He has commanded Armor and Infantry units at every level from platoon to Division, including command of the 1st Armored Division. His service included multiple combat tours. Mr. Pittard brings a wealth of experience in combat vehicle technology and a deep understanding of the Department of Defense and congressional budget processes. He served as the Director of Operations for the Army Training and Doctrine Command, the organization responsible for defining requirements for combat vehicles. As the commander of Fort Bliss, Texas from 2010 to 2013, he transformed the post into one of the largest operational training installations in the Army and was responsible for a community of over 100,000 soldiers, civilians and family members. Mr. Pittard serves as director on the Hamilton County Community Foundation Board. Mr. Pittard also serves on the board of directors of the West Point Association of Graduates. Mr. Pittard holds a bachelor’s degree from the U.S. Military Academy at West Point, a Master’s degree from the School of Advanced Military Studies at the U.S. Army Command and General Staff College and a National Security Fellowship from the John F. Kennedy School of Government at Harvard University.

Mr. Scroggins currently serves as Vice President, General Counsel, a position he has held since joining Allison in December 2007, and Secretary to the Board, a position he held from December 2007 until September 2021 and then reassumed in 2023. He is responsible for advising our Board and leadership team on legal and business matters, managing our legal affairs and overseeing our Government Affairs,Relations, Export Compliance, and Internal Audit organizations and ESG organizations. Prior to joining Allison, Mr. Scroggins served as General Counsel for Product Action International, LLC and was an attorney with the law firm of Ice Miller LLP. Prior to joining Ice Miller LLP,that, Mr. Scroggins worked for the State of Indiana, serving in various roles with the Indiana State Personnel Department, including Deputy Director. Mr. Scroggins received a bachelor’s degree from Ball State University and a J.D. from Indiana University McKinney School of Law.

Ms. van Niekerk currently serves as Vice President, Chief Procurement Officer (formerly titled Vice President, Global Purchasing and Supplier Quality,Quality), a position she has held since 2016. She joined Allison in October 2012 as Managing Director of Purchasing and was promoted to Executive Director of Purchasing in 2014. During her time at Allison, Ms. van Niekerk has spearheaded significant organizational restructuring efforts, including complex contract management strategy, business case development and assessment, sourcing implementation, raw material management, formal supplier development agreements and monthly accrual management. Prior to joining Allison, Ms. van Niekerk held operational responsibility for Navistar Truck Division’s purchasing group. She holds a bachelor’s degree in management from Indiana Wesleyan University.

Based on our review and these meetings, discussions and reports, and subject to the limitations on our role and responsibilities referred to above and in the Audit Committee Charter, we recommended to our Board, and our Board approved, that the Company’s audited consolidated financial statements for the year ended December 31, 20222023 be included in the Company’s Annual Report on Form 10-K. We have also selected PwC as the Company’s independent registered public accounting firm for the year ended December 31, 20232024 and will present the selection to the stockholders for ratification at the Annual Meeting.