Microsoft launched its first retail version of Microsoft Windows on November 20, 1985, and in August, the company struck a deal with IBM to develop a separate operating system called OS/2. Although the two companies successfully developed the first version of the new system, mounting creative differences undermined the partnership. Gates distributed an internal memo on May 16, 1991, announcing that the OS/2 partnership was over and Microsoft would shift its efforts to the Windows NT kernel development.
From Microsoft's founding in 1975 until 2006, Gates had primary responsibility for the company's product strategy. He aggressively broadened the company's range of products, and wherever Microsoft achieved a dominant position he vigorously defended it.
As an executive, Gates met regularly with Microsoft's senior managers and program managers. Firsthand accounts of these meetings describe him as verbally combative, berating managers for perceived holes in their business strategies or proposals that placed the company's long-term interests at risk. He often interrupted presentations with such comments as, "That's the stupidest thing I've ever heard!" and, "Why don't you just give up your options and join the Peace Corps?" The target of his outburst then had to defend the proposal in detail until, hopefully, Gates was fully convinced. When subordinates appeared to be procrastinating, he was known to remark sarcastically, "I'll do it over the weekend."
Gates's role at Microsoft for most of its history was primarily a management and executive role. However, he was an active software developer in the early years, particularly on the company's programming language products. He has not officially been on a development team since working on the TRS-80 Model 100 line, but wrote code as late as 1989 that shipped in the company's products. On June 15, 2006, Gates announced that he would transition out of his day-to-day role over the next two years to dedicate more time to philanthropy. He divided his responsibilities between two successors, placing Ray Ozzie in charge of day-to-day management and Craig Mundie in charge of long-term product strategy.
Gates began to realize the expectations others had of him when public opinion mounted that he could give more of his wealth to charity. Gates studied the work of Andrew Carnegie and John D. Rockefeller and in 1994 sold some of his Microsoft stock to create the William H. Gates Foundation. In 2000, Gates and his wife combined three family foundations into one to create the charitable Bill & Melinda Gates Foundation, which is the largest transparently operated charitable foundation in the world. The foundation is set up to allow benefactors access to how its money is being spent, unlike other major charitable organizations such as the Wellcome Trust. The generosity and extensive philanthropy of David Rockefeller has been credited as a major influence. Gates and his father have met with Rockefeller several times and have modeled their giving in part on the Rockefeller family's philanthropic focus, namely those global problems that are ignored by governments and other organizations. As of 2007, Bill and Melinda Gates were the second most generous philanthropists in
, having given over $28 billion to charity. America
The foundation has also received criticism because it invests the assets that it has not yet distributed with the exclusive goal of maximizing the return on investment. As a result, its investments include companies that have been criticized for worsening poverty in the same developing countries where the Foundation is attempting to relieve poverty. These include companies that pollute heavily and pharmaceutical companies that do not sell into the developing world. In response to press criticism, the foundation announced in 2007 a review of its investments to assess social responsibility It subsequently cancelled the review and stood by its policy of investing for maximum return, while using voting rights to influence company practices. Gates has made The Giving Pledge to donate over half of his wealth to charity.