By Aditya Soni and Deborah Mary Sophia (Reuters) -Days after Chinese upstart DeepSeek revealed a breakthrough in cheap AI computing that shook the U.S. technology industry, the chief executives of Microsoft and Meta defended massive spending that they said was key to staying competitive in the new field.

US tech stocks lost nearly $1 trillion on concerns about artificial intelligence spending, Meta Platforms Inc. hit a record high — signaling that investors were keeping the faith when it came to its own AI plans.

Wall Street's main indexes rose on Thursday, driven by post-earnings advances in Meta and Tesla, although Microsoft's weak cloud forecast and downbeat results from Cigna dampened investor enthusiasm. Microsoft MSFT.O dropped 4.7% after forecasting disappointing growth in its cloud computing business.

Meta Platforms and most other U.S. stocks are rising Thursday following a rush of profit reports from some of the country’s most influential companies, but drops for Nvidia and Microsoft are keeping the market in check.

Investors punished Microsoft with a 6% share drop on Thursday as hefty AI bets failed to drive a big increase in its cloud revenue, while Meta rose 4% after CEO Mark Zuckerberg assured Wall Street about growth with promises of a "really big year".

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.