Steve Ballmer, chief executive of Microsoft, has sold $1.3bn (£800m) worth of shares in the firm.
Ballmer disposed of 49.3 million shares in the past week, bringing his total ownership to 358.9 million shares, or 4.2% of the company, according to a filing with the Securities and Exchange Commission. This is the first time he has sold Microsoft stock in seven years.
"Even though this is a personal financial matter, I want to be clear about this to avoid any confusion," he said in a statement.
"I am excited about our new products and the potential for our technology to change people's lives, and I remain fully committed to Microsoft and its success."
Ballmer said he hopes to sell up to 75 million shares by year-end.
Bill Gates also sold 1 million of shares, worth $27.2m.