Major U.S. stock-indexes lower on Thursday as a fall in commodity prices weighed on energy and materials stocks and investors studied comments by several Federal Reserve policymakers for clues on a widely-expected interest rate hike next month.

Crude oil prices hit Aug lows, while copper and other metal prices tumbled to more than six-year lows, weighed down by a strong dollar, weak Chinese data and concerns about oversupply.

Investors are also keeping a watchful eye on whether the Fed will raise interest rates off near-zero levels in December, a possibility Fed Chain Janet Yellen alluded to last week. Yellen said on Thursday the Fed must weigh impact of the new financial market landscape, but did not comment on the economy or the timing of a rate hike.

Most of Dow stocks in negative area (28 of 30). Top looser - Caterpillar Inc. (CAT, -3.32%). Top gainer - United Technologies Corporation (UTX +0.99%).

All S&P index sectors also fell. Top looser - Conglomerates (-2.3%).

At the moment:

Dow 17441.00 -214.00 -1.21%

S&P 500 2049.75 -19.25 -0.93%

Nasdaq 100 4612.00 -19.75 -0.43%

Oil 41.73 -1.20 -2.80%

Gold 1079.80 -5.10 -0.47%

U.S. 10yr 2.31 -0.03