Or put differently, they can't sell before the lock up expires.
Doesn't mean they will sell as soon as its up, either. But if you can research who the biggest holders are you can guage it. Funds will need to begin selling and distributing post lock-up in order to provide returns to their own investors. Depending on such fund's performance (versus say an SPV who may only hold that stock instead of a basket of others) may dictate how soon before YE this actually occurs.
Remember fund's basis in these companies is (often, not always depending how many financings have been raised) really low so even if a stock gets hit post IPO, they're still likely sitting on gain.
Point of all this is, "easier" to gauge a fund selling off versus members of management or other key individuals at a company with a lock-up.
Doesn't mean they will sell as soon as its up, either. But if you can research who the biggest holders are you can guage it. Funds will need to begin selling and distributing post lock-up in order to provide returns to their own investors. Depending on such fund's performance (versus say an SPV who may only hold that stock instead of a basket of others) may dictate how soon before YE this actually occurs.
Remember fund's basis in these companies is (often, not always depending how many financings have been raised) really low so even if a stock gets hit post IPO, they're still likely sitting on gain.
Point of all this is, "easier" to gauge a fund selling off versus members of management or other key individuals at a company with a lock-up.
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It even says the transaction hasn't closed 
