It very much depends on the circumstances. The founders of Afterpay have made relatively minor reductions in their holdings on 3 separate occasions over an extended period of time. Post those sales there was no dislocation in the company's operations (ie the sales didn't portend an issue within the company) and the share price also performed very strongly post the sell downs.
The founders still own well over $3b worth of stock between them (after total sales of $400m).
In these circumstances it is not a bad sign IMO.
APT Price at posting:
$101.32 Sentiment: Hold Disclosure: Held