Facebook board member Marc Andreessen sold roughly $US54 million ($A52 million) worth of shares in the social networking company to cover taxes he owes on his holdings.
Andreessen's sales are among the latest transactions by Facebook insiders as trading restrictions have expired following the company's May initial public offering.
Donald Graham, chairman and CEO of the Washington Post, who is a director at Facebook, sold roughly US$6.7 million worth of Facebook shares on Monday, according to a regulatory filing on Tuesday.
Both Andreessen and Graham are selling shares to cover tax obligations incurred from the recent vesting or settlement of restricted stock units in the company, Facebook noted in a separate filing earlier this year. Neither intends to sell shares for any other reason, the filing said.
The world's No.1 online social network became the only U.S. company to debut with a market value of more than $US100 billion, but has faced a rough reception on Wall Street amid concerns about its long-term money-making potential.
Shares of the company have risen 20 percent since November 9, finishing Tuesday's regular session at $US23.10, but remain well below their $US38 offering price.
Several executives at the company have also sold shares as the so-called lock-up restrictions on trading have expired.
Facebook COO Sheryl Sandberg sold roughly $US4.2 million worth of Facebook stock on Monday, bringing her total share sales to roughly $US15 million in recent weeks, while engineering vice president Michael Schroepfer sold a little more than $US1 million worth of shares in recent days.
Andreessen, Graham, Sandberg and Schroepfer all sold their shares as part of pre-arranged stock trading plans.