NEW YORK, July 15 (Reuters) - Social media, biotechnology and small-cap names fell in morning trading on Tuesday, cutting gains in other equity indexes, after Federal Reserve chair Janet Yellen said valuations in some sectors appear stretched.
"Signs of risk-taking have increased in some asset classes. Equity valuations of smaller firms as well as social media and biotechnology firms appear to be stretched," Yellen wrote in the Fed's Monetary Policy Report accompanying her statement to Congress.
An ETF of social media stocks fell 1 percent and the Nasdaq biotech index dropped 1.5 percent. The Russell 2000 index of small cap stocks fell 0.7 percent.
The Dow Jones industrial average rose 15.25 points or 0.09 percent, to 17,070.67, the S&P 500 lost 0.49 points or 0.02 percent, to 1,976.61 and the Nasdaq Composite dropped 15.99 points or 0.36 percent, to 4,424.43. (Reporting by Rodrigo Campos; Editing by Nick Zieminski)