As legendary investor Warren Buffett prepares to step down as CEO of Berkshire Hathaway at the end of the year, more leadership changes are taking place—Marc D. Hamburg, the longtime SVP and CFO, is preparing to retire.
Hamburg, who joined Berkshire in 1987, will retire on June 1, 2027, after 40 years of service, the firm announced on Monday. Charles C. Chang will succeed him as SVP and CFO, effective June 1, 2026. Chang is currently SVP, CFO, and director of Berkshire Hathaway Energy. In his new role, he will be based in Omaha and will work with Hamburg during a transition period.
“Marc has been indispensable to Berkshire and to me,” Buffett said in a statement regarding Hamburg’s retirement. “His integrity and judgment are priceless. He has done more for this company than many of our shareholders will ever know. His impact has been extraordinary.”
Chang, 56, joined Berkshire Hathaway Energy in October 2024. Before that, he was a partner in PricewaterhouseCoopers LLP’s energy practice, working with large multinational energy companies. He has 34 years of experience in accounting, U.S. Securities and Exchange Commission reporting, mergers and acquisitions, and sustainability.
Berkshire (No. 6 on the Fortune 500) announced in May 2025 that Buffett will be succeeded by Greg Abel as CEO, who has been vice chairman of Berkshire’s non-insurance operations. Buffett will remain with the company as chairman of the board after the transition.
Abel joined Buffett’s ecosystem a quarter-century ago when Berkshire entered the energy field. As CEO of Berkshire Hathaway Energy starting in 2008, it grew significantly to include a vast portfolio of utilities, pipelines, natural gas plants, and wind/solar farms, Fortune reported. Since 2018, Abel has been serving as vice-chairman of non-Insurance operations at Berkshire.
After a little over a year working as CFO of Berkshire Hathaway Energy, Chang will now join Abel as his strategic partner in leading the entire firm.
Other leadership announcements on Monday include, in insurance operations, that Nancy L. Pierce has been promoted from COO to CEO of GEICO, effective immediately. Pierce joined the company in 1986 and has held leadership roles across claims, underwriting, product management, and regional operations. As part of this transition, Todd A. Combs will conclude his tenure at Berkshire and join JPMorgan Chase, where he has served as a director on its board since 2016. Meanwhile, Adam Johnson, currently CEO of the Berkshire unit NetJets , was appointed president of the Berkshire’s consumer products, service and retailing businesses.
And Michael J. O’Sullivan has been appointed SVP and general counsel, effective Jan. 1. O’Sullivan joins Berkshire from Snap Inc., where he has served as general counsel since 2017. His appointment marks the creation of a new position at Berkshire, which has for decades primarily used external legal counsel for corporate matters.
