Xilinx Inc., the No. 1 maker of programmable semiconductors, said fiscal fourth-quarter sales will be less than expected because customers canceled orders. Sales in the quarter ending this month could fall as much as 15% from the previous period's $450.1 million, said spokeswoman Lori Owen. Analysts polled by First Call/Thomson Financial expected Xilinx to have revenue of $481.3 million. North American resales declined 20% sequentially in January and February, Xilinx said, and international resales are little changed. Xilinx joins fellow chip makers LSI Logic Corp., Cypress Semiconductor Corp., Vitesse Semiconductor Corp. and TriQuint Semiconductor Inc. in cutting forecasts. Rival Altera Corp., the No. 2 maker of programmable chips, last week said it would miss sales and profit expectations. The shares of San Jose-based Xilinx rose 75 cents to close at $43.25 in regular Nasdaq trading before the company reduced forecasts. The stock has fallen 48% in the last year. Xilinx will report fiscal fourth-quarter earnings April 19. It's expected to earn 27 cents a share, according to First Call. The company had a loss in the third quarter because of fewer orders from customers with excess inventory. Altera said sales and profit will fall short of forecasts this year because weak demand and leftover inventory of its chips are causing a slump in orders. Altera said first-quarter sales will fall about 20% from the previous quarter's revenue of $368 million.