Big tech earnings are mostly cheering investors, but AI spending worries are starting to spook some markets.

• Microsoft's cloud business grew faster than expected thanks to AI demand, and it still made strong profit despite spending heavily on AI data centers.
• The Fed kept interest rates unchanged as expected, helping US stocks rise for a third straight day, with chip giant TSMC's US shares also gaining.
• Chipmakers Oracle, SK Hynix, and Micron all jumped on strong results, showing AI chip demand is still driving the sector.
• Google's parent Alphabet missed earnings expectations and reported negative cash flow due to heavy AI spending, sending its stock sharply lower and raising questions about Warren Buffett's big investment in the company.
• SK Hynix expects the global memory chip shortage to last until 2030, meaning demand is far outpacing supply.

Outlook: AI spending will keep pressuring profits at some companies while boosting others, so expect more swings in tech stocks as investors weigh AI costs against AI gains.