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The short interest in Apple Inc. (NASDAQ: AAPL) ticked up by 3.4 million shares to 51 million for the period that ended February 28. Based on shares sold short, it ranked 11th among all companies listed on the Nasdaq.

Apple’s shares have had an extraordinary run. The stock is up 20% this year to $139, which puts it atop the Dow 30 components in terms of improvement. In the past year it is up 36%.

The reasons for the extraordinary run fall mostly into two categories. The first is that Apple’s iPhone sales in the final quarter of last year reached a record, as did the sales of several other Apple products. The company had $78 billion in revenue for the period. In his comments on the quarter, Apple CEO Tim Cook remarked:

We’re thrilled to report that our holiday quarter results generated Apple’s highest quarterly revenue ever, and broke multiple records along the way. We sold more iPhones than ever before and set all-time revenue records for iPhone, Services, Mac and Apple Watch. Revenue from Services grew strongly over last year, led by record customer activity on the App Store, and we are very excited about the products in our pipeline.

Apple’s guidance also was viewed as better than most estimates.

The other and perhaps more compelling reason for the increase in the stock price is the launch of the iPhone 8. Unlike recently released iPhones, analysts expect the new version will add a set of extraordinary new features and retake the leadership in cutting-edge smartphone technology. The widely regarded site MacRumors reported:

Apple has a major iPhone redesign planned for 2017, with a glass body and edge-to-edge OLED display that includes an integrated Touch ID fingerprint sensor and front-facing camera. The new iPhone may be sold alongside upgraded (but standard) 4.7 and 5.5-inch iPhones.

Apple short interest may have ticked up. If earnings from the next quarter rise, and rumors about the iPhone 8 stay strong, that could change.