Founders are selling their stocks, ahead of possible changes in U.S. and state tax laws.

The amounts being withdrawn are huge: On Monday, Amazon founder Jeff Bezos sold more than 11 million shares in the online retailer he founded. The shares opened Tuesday at $285.68.
Yesterday, Amgen Inc. founder and Chairman Joseph Passantino also sold off roughly 11 million shares in the biotech giant.
And the day before, Barry Diller sold nearly 8.8 million shares in Dietz & Myers, which he founded last century.

The trend is especially unnerving for certain types of investors and Wall Street strategists, who think the $1.8 trillion U.S. publicly traded market is overflowing with private company shares.
And though more companies are likely to link up to form American public companies to take advantage of the changes in the U.S. tax code in order to build economic “capital,” they are sending a mixed message to investors.

That tactic is expected to be less appealing for those investors who are increasingly focused on lifetime value in a firm rather than quarterly or yearly earnings.