Facebook Inc. Chief Operating Officer Sheryl Sandberg has sold 946,588 shares, netting about $26.2 million.

In November, Sandberg sold off $7 million in shares.

The most recently included shares were sold in multiple transactions at prices ranging from $27.30 to $27.90 apiece, Menlo Park, California- based Facebook (Nasdaq: FB) reported in a filing with the U.S. Securities and Exchange Commission.

Concerns about executives and company insiders selling off shares have put pressure on Facebook stock. 

Facebook, operator of the world’s largest social network, closed at $27.49 on Dec. 7 and has lost 28 percent since selling shares for $38 each in an initial public offering in May.

With the sale, Sandberg reduced her stake to 18.7 million shares, according to the filing.

Two lockups will expire for some 960 million shares by the end of the year, followed by one for 47.3 million in May 2013.

Theodore Ullyot, general counsel, recently sold 149,075 shares earlier this week, raising $3.13 million.