U.S. stocks open lower after U.S. Fed Chair's speech

U.S. stocks opened lower Thursday as investors reacted to a speech on inflation dynamics and monetary policy from U.S. Federal Reserve Chair Janet Yellen.

Traders are focusing on her comments on inflation, one week after the Fed decided to leave its benchmark rate unchanged. Some analysts believed uncertainty about the timing of interest rate hikes by the central bank had led to increased volatility.

On the economic front, in the week ending Sept. 19, the advance figure for seasonally adjusted initial claims was 267,000, an increase of 3,000 from the previous week's unrevised level, according to the U.S. Labor Department Thursday.

The U.S. Commerce Department announced that new orders for manufactured durable goods in August declined 4.8 billion U.S. dollars or 2 percent to 236.3 billion dollars.

In corporate news, shares of Caterpillar fell over 7 percent in the morning session on Thursday, due to the company's cutting up to 5,000 jobs and lowered guidance.

Shortly after the opening bell, the Dow Jones Industrial Average lost 135.29 points, or 0.83 percent, to close at 16,144.60. The S&P 500 shed 12.81 points, or 0.66 percent, to close at 1,925.95. The Nasdaq Composite Index was down 33.40 points, or 0.70 percent, to close at 4,719.35.

U.S. stocks ended mildly lower after fluctuating between gains and losses Wednesday, as investors assessed European Central Bank President Mario Draghi's remarks about monetary stimulus policy. Endi