Microsoft reported slower-than-expected growth in its crucial Azure cloud business on Wednesday despite beating estimates for overall quarterly revenue, sending its shares down 4% in extended trading.

Microsoft has tested Wall Street's patience by plunking down huge amounts of cash in pursuit of profits from AI that have yet to satisfy investors.

Microsoft on Wednesday forecast disappointing growth in its Azure cloud computing business, sending its shares down more than 5% as investors worry about big spending, elusive artificial intelligence revenue and growing competition from cheaper AI models from China.