SEATTLE, United States — Amazon.com Inc. reported disappointing sales in the holiday quarter and said revenue in the current period may miss estimates, raising concerns that rising spending on warehouses, movies and gadgets is not yet translating into fast enough growth.

Revenue increased 22 percent to $43.7 billion in the fourth quarter. Net income was $749 million, or $1.54 a share, the Seattle-based company said Thursday in a statement. Analysts estimated profit of $1.36 on revenue of $44.7 billion, according to data compiled by Bloomberg. Sales in the current quarter will be $33.3 billion to $35.8 billion, the company said. Analysts projected $36 billion.

Amazon Web Services revenue was $3.5 billion in the fourth quarter, up 47 percent from a year earlier. Cloud computing is Amazon’s fastest-growing and most profitable segment.

Operating expenses rose 23 percent to $42.5 billion in the quarter.

The world’s largest online retailer is dominating e-commerce in the US with its $99 Amazon Prime subscription, which includes delivery discounts, music and video streaming and photo storage that keep shoppers engaged with Amazon and off competing sites. Still, investors are concerned about the unpredictable nature of Amazon’s spending.

Shares fell as much as 4.7 percent in extended trading after closing at $840.18. The stock had gained more than 10 percent over the past month in anticipation of a strong holiday period.

By Spencer Soper; editors: Jillian Ward and Andrew Pollack.