:Investors punished Microsoft with a 4 per cent share drop on Thursday as hefty AI bets failed to drive a big increase in its cloud revenue, while Meta rose 2 per cent after CEO Mark Zuckerberg assured Wall Street about growth with promises of a "really big year". The chief executives of both the companies defended their heavy investments on artificial intelligence on Wednesday, days after Chinese upstart DeepSeek unveiled a breakthrough in cheap AI that shook the technology industry. But while