Updated from 9:25 a.m. EDT

National Semiconductor

(NSM)

shares fell nearly 15% Wednesday after the company warned that revenue in its fiscal first quarter would fall well short of prior guidance and Wall Street expectations.

The stock was recently off $2.34 to $13.36. Other chip names showing early weakness included

Xilinx

(XLNX) - Get Report

,

STMicroelectronics

(STM) - Get Report

and

Altera

(ALTR) - Get Report

.

The Santa Clara, Calif.-based analog chipmaker said after the bell Tuesday that it expects sequential sales for the quarter ending Aug. 29 to decline 4% to 5% from the $571.2 million sales level of the prior quarter, implying sales as low as $543 million. That compares with previous guidance, issued June 10, for revenue to be flat to up 3%.

Wall Street analysts were expecting revenue of $582.9 million for the period with earnings per share of 31 cents. National Semi didn't comment on its earnings expectations today.

National Semi draws about one-third of its sales from the cell phone market, with another quarter of its revenue split between PCs and displays.

Explaining the shortfall, National Semi said it had seen lower-than-expected turns orders (those placed and delivered within the same quarter). The company said distributors had slowed the pace of orders in the quarter, while demand for components that go into flat-panel displays and Chinese wireless handsets had proven weaker than expected.

The company will give a financial report on its first quarter on Sept 9.