The 58-year-old, who retired Feb. 4 after serving 33 years at the Redmond, Washington-based company, owns 333.2 million shares of Microsoft, 3.1 million more than Gates. Ballmer has collected about $3.4 billion selling shares since the company’s 1986 initial public offering, and has a net worth of $18.9 billion, according to the Bloomberg Billionaires Index.

“It’s not an event in and of itself, but it is symbolic in that it speaks to what has taken place at Microsoft over the last 10 years,” Daniel Ives, a New York-based analyst at FBR Capital Markets & Co., said by phone. “There’s been a passing of the guard.”

Ballmer joined Microsoft as employee No. 30 in 1980 after Gates persuaded him to drop out of Stanford University’s business school. He rose to the rank of president and then took over for Gates as CEO in 2000.

Bridgett Arnold, a spokeswoman for Gates, declined to comment in an e-mail. Microsoft spokesman Peter Wootton also declined to comment.

Microsoft fell 31 cents to close at $39.69 in New York.