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Alternatively, they are informing the market of their perceived value of the company.

Or rationally reacting to having their net worth concentrated nearly entirely in a single security. Contrary to essentially all financial advice.

...and? Would the company not do the equivalent to them?

Former "owners" after selling stock. And if people building and running company don't want to own it anymore...

It could well be that the employees did that after management made decisions that they feel gutted the value of the company anyway.