NEW YORK — Stocks plummeted this morning after the Federal Reserve indicated that the U.S. economic slump could last for years.

At 9:50 a.m., The Dow Jones industrial average fell 371 points, or 3.3 percent, to 10,753.

The Standard & Poor’s 500 index fell 37, or 3.2 percent, to 1,129. The Nasdaq composite fell 81, or 3.2 percent, to 2,457.

On Wednesday afternoon, the Fed announced a portfolio rebalancing designed to drive down interest rates on long-term government debt. The move was largely expected, but stock markets began a late-day slide that carried over to overseas markets today.

Analysts say the news troubled investors for two reasons: the Fed’s statement offered a bleak assessment of the future of the U.S. economy, saying it sees “significant downside risks to the economic outlook” including volatility in overseas markets.

Secondly, the Fed also decided to buy bonds that matured after 30 years, hoping to push down rates far into the future.