Nvidia announced a $50 billion stock buyback as part of its fiscal second-quarter earnings, where it reported impressive financial results that exceeded Wall Street expectations. The company returned over $15 billion to shareholders in the first half of its fiscal year and has more than $7 billion remaining under its current repurchase plan. Nvidia's stock dropped 4% in extended trading despite the strong earnings report. Some experts suggest that Nvidia's consistent success may make it challenging to impress investors.