Amazon.com Inc. dropped after projecting weaker-than-expected operating income and trailing the sales growth of its cloud rivals, leaving investors searching for signs that the company’s huge investments in artificial intelligence are paying off.

The tech giant expects total net sales to be between $174.0 billion and $179.5 billion in the third quarter, compared with analysts’ average estimate of $173.08 billion.

Amazon stock fell after the tech giant posted second-quarter earnings above expectations, but offered a mixed outlook.