Amazon (AMZN) is losing one of its greatest pricing advantages with the expiration of a tax loophole relic from the earliest days of the e-commerce era. More and more states are charging the company sales tax, leveling the playing field on pricing and raising an estimated $8.6 billion in additional revenues for states.

Victor Anthony of Topeka Capital Markets says the tax hikes won't matter. Citing "no material difference" between revenue growth rates in markets where Amazon is taxed and not taxed, Anthony says Amazon continues to be all about growth against online competitors. Amazon is taking share in the online world, he notes, no mean feat for the dominant internet retailer.

The real leverage will kick in for Amazon next year when they reduce investments in Kindle and Cloud initiatives that are causing expenses to rise in the near term but setting the stage for market share grabbing profitability down the road.

Amazon's lofty multiples are always based on the idea that the company will be able to successfully invest for the long term. The question for investors is whether or not this is a sustainable advantage. Once investors sense that CEO Jeff Bezos has lost his touch the multiple contraction could be fierce.

Until then Amazon will continue to be the one of the toughest stocks to short in the investing universe. For now at least, there doesn't seem to be anything the IRS or any other retailers can do to stop Amazon.