On Tuesday, she sold about 176,000 shares, worth about $3.75 million.
Last week she sold about twice as many, worth an estimated $7.4 million.
Facebook engineering VP Mike Schroepfer also sold $663,000 worth of shares this week.
This is all part of a pre-planned Facebook "lockup" release in which Facebook executives can start cashing in on company shares.
The first release hit on October 29. The second, larger release of shares will hits on November 14. The third will strike a month after that.
Over the six week time period, nearly 1.2 billion Facebook shares will become available.
Sandberg and Schroepfer have set up a 10b5-1 trading plan, an SEC-approved method for insiders to automatically sell shares, as have other Facebook executives. Since Facebook executives have disclosed those plans in SEC filings, it's reasonable to expect periodic share sales under them.
Sandberg owns about $720 million worth of Facebook, so the $3.75 million she just sold is a fairly small portion of that.
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