Google parent Alphabet Inc.’s shares dropped after slower growth in its cloud business contributed to lower-than-expected revenue in the fourth quarter.

Alphabet shares fell 8% on Wednesday as investors balked at the Google parent's slowing cloud growth and planned $75 billion capital spending for the year, underscoring growing fears over Big Tech's escalating artificial intelligence costs.

CEO Sundar Pichai defended the dramatic increase on a conference call with analysts, who are raising new questions about capital spending.