None of those people could sell anything (never mind everything) in March without violating law, unless that selling aligned with preexisting 10b5 plans to sell. You can look at the insider action[0] yourself, everything but the Becker sale looks like routine sale / disposition of options/equity comp, and even that isn’t that aberrational compared to his sales in ‘22 and ‘21.

I think you’re right about the proportional sizes, but it looks like the other officers only held a few thousand shares each, so routine grant/sale transactions were a much larger share of their individual holdings.

[0] https://www.nasdaq.com/market-activity/stocks/sivb/insider-a...