For the first time in Microsoft’s history, Bill Gates is no longer the company’s largest individual shareholder, as of this afternoon.

A stock sale by Gates made public a few minutes ago reduced his ownership to 330.1 million shares, compared to more than 333 million owned by former Microsoft CEO Steve Ballmer as of the company’s last proxy filing.

Gates has been steadily selling Microsoft shares for years, at an average of 80 million shares annually, primarily to endow the Bill & Melinda Gates Foundation, funding its philanthropic work in education and global health. Gates stepped down as Microsoft chairman when the company named Satya Nadella as its new CEO, but said he would be spending more time at the company as an adviser.

The transaction that took Gates below Ballmer’s stake was a sale of 4.6 million shares on April 30, at a price of $40.34, bringing the Microsoft co-founder’s shares to 330,141,164, or just under 4 percent of the company. Microsoft’s shares closed at $39.69 today.

The Microsoft co-founder’s status as the largest shareholder dated back to the early days of the company, in the mid-1970s.

In his 2011 memoir, Microsoft co-founder Paul Allen wrote that he had originally envisioned his partnership with Gates as a 50-50 split, but Gates convinced Allen to take 40 percent, because Allen had taken a salary from his work for Altair maker MITS during the early days. Later Gates convinced Allen to go even further and change the split to 64-36 in Gates’ favor.

Ballmer held more than 333 million Microsoft shares, or just under 4 percent of the company, as of the company’s most annual proxy filing last fall, and SEC filings indicate no further sales by the former Microsoft CEO in the time since.

Announcing his retirement plan last August, Ballmer wrote in an email to employees, “I cherish my Microsoft ownership, and look forward to continuing as one of Microsoft’s largest owners.”