US stocks end lower after busy earnings day

US stocks fell for a third straight session Thursday as disappointing earnings from Caterpillar, American Express and others overshadowed some stronger reports.

At the closing bell, the Dow Jones Industrial Average stood at 17,733.52, down 117.52 points (0.66 percent).

The broad-based S&P 500 dropped 11.91 (0.56 percent) to 2,102.24, while tech-rich Nasdaq Composite Index lost 25.36 (0.49 percent) at 5,146.41.

Dow members American Express (-2.5 percent), Caterpillar (-3.6 percent) and 3M (-3.7 percent) all fell sharply following earnings reports. But General Motors gained (+4.0 percent) after reporting second-quarter earnings quadrupled from a year ago.

"Earnings overall have been better than expected, but still not very good," said David Lynch, portfolio manager at Kenjol Capital Management.

"The valuations on the market are not cheap... so we're going to need to see earnings growth for the market to make progress."