As reported earlier this week, the Microsoft chairman is looking to sell his shares at a time when the stock has climbed roughly 40 percent since the start of the year.
Gates's pending sale is valued at $198.9 million, according to the filings.
The sale also follows Gates's foray into art trading. He reportedly made art history recently when he paid $30 million for a seascape painting by Winslow Homer. That acquisition price set a new high for an American painting, according to a report earlier this week in the New York Times.
Tom Pilla, a Microsoft spokesman, declined to comment on the painting, but noted that Gates's pending sale is not unusual for the software giant's chairman and CEO.
"This is part of Bill's regular stock selling program, designed for prudent diversification," Pilla said.
The pending sale represents less than 1 percent of Gates's holdings, which stand at more than 530 million shares. It comes one month after Microsoft posted a robust 25 percent increase in net income for the quarter ending March 31, fueled by strong demand for its products.
Microsoft posted net profits of $1.34 billion, up from $1 billion reported a year ago. Revenues rose to $3.77 billion, up 18 percent from the previous year.