SAN FRANCISCO -- Intel ( INTC) sharply reduced its fourth-quarter sales expectations Wednesday, citing "significantly" weaker-than-expected demand in all regions and across all product types.Shares of Intel were down 7%, or $1, at $12.51 in extended trading Wednesday. The world's No. 1 maker of PC microprocessors said revenue in final three months of the year is now expected to be $9 billion, plus or minus $300 million, instead of its previously forecasted range of $10.1 billion to $10.9 billion. Intel also said its gross profit margin in the quarter will be 55%, plus or minus a couple of points, instead of the 59% level previously expected. The news comes a week after CEO Paul Otellini described the current economic slowdown as the worst he'd seen in his lifetime. And it comes a day before rival Advanced Micro Devices ( AMD) is slated to host an annual briefing with financial analysts. The new forecast means Intel's sales will decline between 9% and 15% sequentially in the fourth quarter, a major slowdown for Intel, which typically counts the last three months of the year as one of its strongest periods. The last time Intel's sales actually decreased sequentially in the fourth quarter was 1984 (In 2000, Intel's fourth-quarter sales were essentially flat sequentially). With unemployment rising in the U.S. and the economy headed for a recession, consumers are holding off on buying everything from new cars to PCs. And spending by corporations looks equally bleak.