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

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

Alphabet said on Tuesday it will spend $75 billion on its AI buildout this year, 29% more than Wall Street expected, and investors signaled disappointment at a missed cloud revenue target and began showing impatience over profitability.