Apple (AAPL) recently decided to buy startup Sonera, which has reportedly developed a neural-data technology tool. The move could boost Apple stock within the next few years and bodes well for the company's long-term outlook. In the medium term, however, AAPL stock is unlikely to surpass the returns of the Nasdaq-100 by a significant margin, as the company continues to face multiple, negative catalysts. Weaker-than-expected revenue-growth guidance for the current quarter also suggests that these factors are beginning to weigh on Apple's performance. Let's take a closer look.