Shares in the Google parent Alphabet fell double digits Wednesday evening into Thursday trading, erasing hundreds of billions of dollars in stock market value from the $4tn tech giant.

The company had reported lower-than-expected profit and a slowdown in its advertising business while it maintained big spending on AI.

Net profit slid 25% from a year earlier to $26.2bn in the July-to-September period, or $2.12 a share, well short of expectations by analysts surveyed by FactSet.

Alphabet booked an $8.7bn loss on its equity investments, which it attributed to its stake in SpaceX, the Elon Musk-led company where shares have struggled since going public in June.

Revenue, however, rose 25% to an enormous $127.6bn. The figure was slightly below the roughly $128bn analysts had forecast.

Advertising revenue grew 11% to $82bn, short of expectations.…