In the two weeks before Facebook's latest struggles, CEO Mark Zuckerberg sold 1.14 million shares as part of regularly scheduled programs.
That was the most insider selling for any public company, going back as far as three months, according to Argus Research's Vickers Weekly Insider.
In the Facebook case, Zuckerberg and another executive sold shares about $20 above where they were trading Tuesday.
Analysts are not suggesting anything nefarious behind the regularly scheduled sales. However, the sheer volume of the selling can amount to an overhang on the stock at a time when it could use all the support it can get.
Facebook shares dropped 6.77 percent into correction territory Monday, the first trading day after a data scandal involving 50 million accounts added to concerns about user privacy. Facebook shares traded 5.3 percent lower near $163 Tuesday afternoon.