NEW YORK (AP) - Wall Street turned lower Friday as skittish investors, unable to hold on to much optimism about the economy, drew little comfort from President Bush's economic stimulus plan.

Investors had already pulled back from a big early gain, with the major indexes trading mixed as Bush began to speak. By the time the president finished announcing a plan for about $145 billion worth of tax relief, the indexes were well into negative territory.

"It's disappointed in the size of the economic growth package. Wall Street's showing its displeasure," said Kim Caughey, equity research analyst at Fort Pitt Capital Group in Pittsburgh. "Honestly, I think the institutional investors understand the limits to the government's ability to enact economic change."

The Dow Jones industrial average, up more than 180 points in morning trading, was down 58.61, or 0.48 percent, at 12,100.60 minutes after Bush finished speaking. The Dow plunged 306 points Thursday amid deepening pessimism about the economy.

The broader Standard & Poor's 500 index fell 13.72, or 1.03 percent, to 1,319.53, while the technology-focused Nasdaq composite index fell 9.40, or 0.40 percent, to 2,337.50.