Amazon is still a beast.

The U.S. Supreme Court has ruled in favor of South Dakota in a case against Wayfair (W)  that looked at whether Web retailers have to collect state sales taxes on online sales. The vote, a surprisingly close 5-4, overturned a 1967 ruling that had prohibited states from collecting sales taxes from retailers who didn't have a physical presence in the state in question. However, that older ruling was obviously made without the Internet in mind, and was only intended to govern mail-order transactions.

As a result, un-taxed online retail sales have been costing the states an estimated $33.9 billion per year in lost tax revenues. Bricks-and-mortar retailers also complained that this "loophole" left them disadvantaged against their Internet-based competitors.

It's true that Amazon (AMZN)  and some online retailers already collect sales taxes on behalf of states (although Amazon only does so on its own sales, not for the most part on sales made by third-party vendors who operate on the Amazon Marketplace). That might be why Amazon was only down 1.1% on Thursday after the verdict came out -- just barely underperforming the Nasdaq Composite's 0.9% loss. Similarly, Wayfair only saw its shares decline 1.6%, and the firm announced that it already collects sales tax on 80% of its U.S. transactions.

However, other e-tailers didn't perform as well following the verdict. For example, eBay (EBAY)  suffered to the tune of -3.2% Thursday, while Overstock (OSTK)  tumbled 7.1%.

I think eBay's reaction to the verdict made a particularly important point. The firm said in a statement that "if state tax authorities attempt to subject remote small businesses to audits and lawsuits, there will be increased litigation across the country to protect small business from unfair burdens."

Stay with Action Alerts PLUS holding Amazon nonetheless, it's headed to $1,850.

At the time of publication, Guilfoyle was long AMZN.