Looks like Nvidia (NVDA) - Get Report will end 2016 as the best-performing stock in the S&P 500. The shares are up 238% this year. But the bears have recently come out of hibernation on the stock.

In November, I said I thought shares of Nvidia were too hot to handle. Though I remain bullish on the company's long-term prospects, you have to recognize that momentum investors are in control, and the stock is a better buy at $90 than it is at $111.

Last week, a noted short-seller took to Twitter to point out some of the flaws in the Nvidia investment thesis. Specifically, Nvidia's growth in gaming has come at the expense of AMD (AMD) - Get Report as opposed to creating new markets. There is significant competition in the data center business. And Intel (INTC) - Get Report could impact Nvidia's gross margin unfavorably as Intel jumps into the market in mid-2017.

These are all valid points.

At one point, long ago, AMD supplied 30% of gaming processors, but today, AMD's market share is in the low teens. Nvidia has an estimated 87% share in the gaming business.

AMD CEO Lisa Su has repositioned AMD toward growing markets like artificial intelligence and PC gaming. In addition, AMD will finally begin to ship parts in a 14-nanometer die size, something that Intel has been doing since 2014. The refreshed product lineup is important because the chips are faster and use less power, so AMD's products will be much more competitive in the enterprise server market.

Competition is heating up, and Nvidia investors could be in for a few sleepless nights.

The bulls point out that there are an estimated 100 million gamers out there, and that NVDA has a $10 billion opportunity out in front of it. In Nvidia's most recent quarter, gaming sales grew by 54% year over year. Bulls also point out Nvidia's Pascal cards have higher average selling prices, and the step-up in average selling prices will power the company's margins and earnings.

The artificial intelligence and deep learning market could be as large as $10 billion, so there's plenty of room for competitors. Besides, Nvidia is estimated to have an 80% market share right now, so competitors would have to work hard to overcome the early groundwork the company has already laid.

The bulls finally point out that the auto market is nearly 10 times as large as the server business. Nvidia has a huge lead. Its embedded processors are providing artificial intelligence processing for autonomous vehicles. The Xavier platform and the Drive PX2 autopilot system allow carmakers to collect and process tremendous amounts of sensor data while the car is moving. The platform also allows carmakers to display high-definition mapping and navigation systems within the automobile.

The Drive PX2 platform will power a new autopilot system in Tesla Motors' (TSLA) - Get Report roster of factory-produced vehicles -- the Model S, the Model X and the upcoming Model 3.

I still think Nvidia has some of the best top-line growth in the semiconductor business, but I would wait for a correction to buy the stock.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.