Facebook Inc (NASDAQ:FB) shares have been doing incredibly well since the company’s last earnings report, and this morning they remain just slightly above the $38 initial public offering. However, they have yet to crack their opening day price, and already insiders are selling off their shares.

Facebook COO Sheryl Sandberg

Sheryl Sandberg sells 2.37 million Facebook shares

Regulatory filings indicate that Chief Operating Officer Sheryl Sandberg sold almost 2.4 million shares of Facebook Inc (NASDAQ:FB) at a price of around $38 per share. She raked in about $91 million from the sale of those shares. However, that’s just a small fraction of her holdings in the company, according to Emily Jane Fox of CNN Money. Her most recent sale of shares amounted to just 5 percent of her total holdings.

Sandberg has been gradually selling off her shares as part of a pre-arranged trading plan. This is a way for insiders to sell their stock by planning ahead before any information about the company is released. It helps insiders avoid being accused of insider trading because they had the plan in place before any details about potentially market moving information about their company comes out in the media.

Sandberg joins other Facebook insiders

She isn’t the only one who has been selling off Facebook Inc (NASDAQ:FB) shares since the company’s stock hit its IPO price. Earlier this month a handful of other insiders were also spotted via regulatory documents selling their shares. Chief Financial Officer David Ebersman, Engineering Vice President Michael Schroepfer, General Counsel Colin Stretch, Chief Accounting Officer Jas Athwal and Marketing Vice President David Fischer have also been selling their stock according to prearranged trading plans.

Of course it’s important to note that these insiders each still own sizeable quantities of Facebook shares. Also one name that’s noticeably missing from this list is Facebook Inc (NASDAQ:FB) Chief Executive Officer Mark Zuckerberg. He said in September that he would hold onto his shares of the company for at least a year. Regulatory filings earlier this year showed that he owned almost a third of the social network he founded.