Shares of Akamai Technologies Inc., a company that helps customers speed the delivery of online content, tumbled late Wednesday after sales missed estimates.

Fourth-quarter sales climbed 17 percent to $378 million, the Cambridge, Massachusetts-based company said in a statement. That trailed the $381.4 million predicted by analysts on average, according to data compiled by Bloomberg.

The results showed signs of softening demand for Akamai’s services, which help customers such as news sites and e-commerce retailers speed up their online offerings, said Chad Bartley, an analyst at Portland, Oregon-based Pacific Crest Securities.

“Revenue was definitely lighter than expectations,” he said. “Growth decelerated quite a bit in the fourth quarter.”

In aftermarketing trading, Akamai shares were quoted down 16 percent at $34.90. The stock, up 1.6 percent this year, had closed at $41.58 in New York.

In December, Akamai named co-founder Tom Leighton as its next chief executive officer after an eight-month search. He took the job on Jan. 1.