https://finance.yahoo.com/news/u-top-court-lets-states-142402427.html

The ruling opens the door to a new revenue stream to fill state coffers - up to $13 billion annually, according to a federal report - while imperiling a competitive advantage that e-commerce companies had over brick-and-mortar rivals that already must collect sales tax.

Shares of online retailers fell sharply following the ruling, with Wayfair down 3.8 percent, Overstock off 2.1 percent and Etsy Inc shares off 4.4 percent. Amazon.com Inc shares fell as much as 1.9 percent before paring losses. Amazon was among the biggest drags on the benchmark S&P 500 stock index.