(Reuters) - Nvidia Corp NVDA.O on Monday cut its fourth-quarter revenue estimate by half a billion dollars because of weak demand for its gaming chips in China and lower-than-expected data center sales, sending its shares down 15 percent.

The warning adds to concerns that a slowdown in the world’s No.2 economy, exacerbated by an ongoing trade war with the United States, will continue to squeeze sales and profits at technology companies. Nvidia’s caution signaled more challenges for the micro chip industry after mixed quarterly results from major companies last week.

“Q4 was an extraordinary, unusually turbulent, and disappointing quarter,” Chief Executive Officer Jensen Huang said.

The company forecast revenue of $2.20 billion for the quarter ended Jan. 27, down from its earlier forecast of $2.70 billion. Both numbers were plus or minus 2 percent.

Analysts on average had forecast revenue of $2.7 billion, according to Refinitiv data from IBES.

Shares of Nvidia were down 13.9 percent at $137.91 in morning trade.

Nvidia in November forecast holiday quarter sales $700 million below analyst expectations, hit by unsold chips piling up with distributors and retailers after the evaporation of the cryptocurrency mining boom.

“This incremental $500 million miss in addition to the original $700 million miss is quite underwhelming for investors,” said Kinngai Chan, an analyst with Summit Insights Group.

Data center revenue, which accounts for nearly a third of Nvidia’s sales, fell short as a number of deals did not close in the last month of the quarter.

“Customers shifted to a more cautious approach,” the company said.

That echoed sentiment from rival Intel Corp INTC.O, which last week reported lower-than-expected fourth-quarter sales and forecast a tepid current quarter.

Nvidia said sales of its next generation Turing graphic chips, launched in August last year, were also below expectations as some customers delayed their purchases.

Turing chips technology helps game creators make real-time cinema-quality visuals by simulating the physical behavior of light.

Nvidia expects gross margin of 55 percent, plus or minus 100 basis points, for the fourth quarter on a GAAP basis, its worst in at least three years.

“They probably have to clear out what’s not selling, which hits margins,” Elazar Advisors analyst Chaim Siegel said.

Nvidia will report its fourth quarter results on Feb. 14.