500k is not a large volume, he still owns over 13M shares. Probably sold a few shares to take care of personal expenses, etc,.. nothing really uncommon. But the main thing is he holds over 13M shares.
That's not anything to be worried about. It's only about 3.6% of what he owned. One of the directors on our board sold 17.5 million dollars worth of his shares. Yes I mean 17.5 million$$, not shares, and we are still in business lol