The 4mil+ share trade posted after close was a from T trade.
That means that the 4mil+ shares were sold off in small increments over time, and the total amount is reported at the end.
It's done when someone wants to sell a bunch of stock without potentially tanking the PPS with a trade like that all at once. Might explain some of the increased selling we saw over the course of today. Probably just someone trying to exit a little more gracefully now that it's come back up a little bit again.
Though I've seen about that size of a trade go through at once for HYGN just watching it recently, and it didn't seem to impact the PPS much. Wonder why they did it that way...
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