SAN FRANCISCO >> Bill Gates is stepping down from the board of Microsoft, the software giant he helped found more than four decades ago.

Gates said today that he would also step down from the board of Berkshire Hathaway, the conglomerate run by his close friend, Warren Buffett.

“I have made the decision to step down from both of the public boards on which I serve — Microsoft and Berkshire Hathaway — to dedicate more time to philanthropic priorities including global health and development, education, and my increasing engagement in tackling climate change,” Gates wrote in a LinkedIn post.

For decades, Gates was the face of Microsoft. Known for his technical acumen and ruthless business practices, he helped to establish Microsoft’s Windows software as the primary system for the personal computer. Microsoft said Gates would remain a technical adviser to the company.

Gates has slowly been stepping back from Microsoft in recent years. He left his day-to-day role at the company in 2008 and served as the board’s chairman until 2014.

The company said he wants to devote more of his time to his philanthropy at the Bill & Melinda Gates Foundation, one of the world’s biggest nonprofit organizations, which was started with the billions of dollars he made from Microsoft.

Gates remains one of the largest individual shareholders of Microsoft. As of December, he held more than 100 million shares of Microsoft, roughly 1.3% of the company’s shares. His stock is worth about $16 billion. He said he would remain active at the company and would work closely with Satya Nadella, Microsoft’s chief executive.

“Microsoft will always be an important part of my life’s work and I will continue to be engaged with Satya and the technical leadership to help shape the vision and achieve the company’s ambitious goals. I feel more optimistic than ever about the progress the company is making,” Gates wrote in his post.

In his post-Microsoft career, Gates has become better known for his work in fighting infectious diseases and climate change. Last month, the Gates Foundation said it would commit an additional $100 million to fight the coronavirus. The organization pledged $10 million earlier in the year.

He has persuaded Buffett, his bridge partner and neighbor on the list of the world’s richest people, to donate most of his fortune to the Gates Foundation.

Gates joined the Berkshire Hathaway board in 2004. The conglomerate has nominated Kenneth Chenault, the former chief executive of American Express, to replace Gates on the board.

Daniel Ives, managing director of equity research at Wedbush Securities, said in a research note that Gates stepping down from the Microsoft board was not a surprise and that it was a vote of confidence for Nadella and the direction of the company.

Gates founded Microsoft in 1975, dropping out of Harvard and joining Paul Allen, his friend and technology collaborator since their teenage years at a private high school in Seattle. In 1975, they moved to Albuquerque, New Mexico, where a fledgling microcomputer company, MITS, made the Altair 8800, a primitive machine often credited as the first personal computer.

Microsoft’s first product was a version of the BASIC programming language that could run on the underpowered Altair computer. That was the start. Later, after Gates moved Microsoft to suburban Seattle, a succession of highly successful commercial products followed — the MS-DOS operating system, the Windows operating system and the Office collection of productivity programs, including Word, Excel and PowerPoint.

By the mid-1990s, Microsoft was the dominant personal computer software company, so much so that it became the target of a series of antitrust investigations. In a landmark federal case, a lawsuit filed in 1998, Microsoft was eventually found to have repeatedly violated the nation’s antitrust laws.

Gates stepped aside as chief executive in 2000, after the antitrust ruling. In recent years, his main occupation has been as a philanthropist, donating billions to world health and disease eradication programs.

But the antitrust battle of 1990s still rankles Gates. At a New York Times DealBook conference last fall, he was asked if the suit made the technology market more competitive. “No,” Gates replied. “Everyone else can say that if they want. It’s not true to me, and I will never change that opinion.”