Stocks fell sharply yesterday as a sell-off, sparked by deepening fears about the earnings of semiconductor makers, again threatened to push the Dow Jones Industrial average below the 10,000 mark.

Investors were also spooked the prospect of a slowdown in advertising spending, which eroded support beneath traditional and new media companies.

But the semiconductor group suffered the most concentrated selling, with Teradyne and Micron Technology dropping to lows not seen in more than a year.

The bears' mauling of the group took nearly 10 percent off the widely watched Philadelphia Stock Exchange semiconductor index.

The Dow closed down 149.09 points at 10,089.71, while the broader Standard & Poor's 500 index fell 24.65 points to 1,349.97.

The Nasdaq composite index dropped 76.35 points to 3,213.93.