What happened Shares of Applied Optoelectronics (NASDAQ: AAOI) gained 58% in July 2017, according to data from S&P Global Market Intelligence. Yes, the stock gained 58% in a single month. That's not a typo. So what The maker of high-speed transceivers and other components for fiber-optic networking equipment was already on a massive roll at the start of July, having soared nearly 200% higher in the first six months of 2017. And then the train kept rolling. AOI released preliminary second-quarter results on July 13, exceeding management's own guidance targets by wide margins. An avalanche of analyst upgrades and target price boosts followed, and AOI's share prices jolted upward with every rosy research note. Image source: Getty Images. Now what Analyst firm BWS Financial broke from the jubilant crowd to issue a sell rating on AOI with a hugely negative target price of $25 per share on July 20. Its theory is that largest customer, Amazon.com (NASDAQ: AMZN), has been ordering high-speed optical transceivers from AOI rival Fabrinet (NYSE: FN) recently, arguably pointing to lost sales for this highflier. The markets simply shrugged off that complaint and AOI's rise continued. Amazon could simply be ordering more transceivers on top of the large supply AOI can provide. Consider this quote by Applied Optoelectronics CFO Stefan Murry from the first-quarter earnings call in May: "Right now, we're basically shipping everything we can manufacture. So the growth rate is not dependent on demand. It's dependent on our ability to continue to ramp our manufacturing." Murry added, "There's a limit to how fast we can increase our production capacity. So that's really the limiting factor to the growth rate." So Amazon might be wise to expand its component sourcing to another supplier -- and that's not necessarily bad news for AOI at all. 10 stocks we like better than Applied OptoelectronicsWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the 10 best stocks for investors to buy right now... and Applied Optoelectronics wasn't one of them! That's right -- they think these 10 stocks are even better buys. Click here to learn about these picks! *Stock Advisor returns as of July 6, 2017Anders Bylund owns shares of Amazon. The Motley Fool owns shares of and recommends Amazon. The Motley Fool has a disclosure policy.