Investors should note that later this week 8.8 percent of Facebook's outstanding stock, or more than 170 million shares, could become available as the lockup period expires for stock sold during the WhatsApp acquisition. If the company reports a big earnings miss, this could spur selling, Mahaney said. "If there is a real negative surprise that lock-up expiration will amplify the downwards move," Mahaney said. "If there are positive results, I don't think you'll have a major hit to the stock from the downside." Read More