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Following a report this morning that Amazon.com Inc. (NASDAQ: AMZN) has filed a trademark application on a phrase that refers to prepared food kits, shares of Blue Apron Holdings. Inc. (NYSE: APRN) tumbled as much as 12% to $6.51, — 35% below the company’s initial public offering (IPO) price of $10.

Blue Apron’s IPO came just a few day after Amazon announced its agreement to acquire Whole Foods Market Inc. (NASDAQ: WFM) for $13.7 billion.

Amazon filed a trademark application on the phrase: “We do the prep, you be the chef.” The e-commerce giant said the phrase covers “Prepared food kits composed of meat, poultry, fish, seafood, fruit and/or and vegetables and also including sauces or seasonings, ready for cooking and assembly as a meal,” according to a report at MarketWatch.

Amazon’s massive customer base, including some 85 million Amazon Prime subscribers, could punch a serious hole in the plans of Blue Apron and other startups seeking to play in the meal delivery business.

The big problem is customer acquisition costs. It’s a marketing truism that keeping a customer you already have is much cheaper than drumming up new ones. And while Blue Apron reported in its IPO filings that it had 1 million subscribers averaging just over 4 orders each, the average order value fell from $59.28 in the first quarter of 2016 to $57.23 in the first quarter of 2017.

Now that Amazon appears poised to enter the meal-kit market, Blue Apron faces a truly formidable challenge. It’s worth noting, however, that companies frequently file for trademarks they have no intention of using, either because they changed their mind or because it was just a nuisance filing aimed at keeping a competitor away from the golden words.

Blue Apron’s stock price has recovered a bit, trading down 10.6% at $6.58 at the noon hour Monday. The stock’s post-IPO range is $6.51 to $11.00.