US STOCKS-Dow, S&P gain on Yellen; Nasdaq ends down for 2nd day
* Yellen cites housing, geopolitical tensions as economic risks
* Alibaba IPO filing pressures Yahoo shares
* Dow up 0.7 pct; S&P 500 up 0.6 pct; Nasdaq off 0.3 pct (Updates to close)
By Angela Moon
NEW YORK, May 7 (Reuters) - U.S. stocks mostly rose on Wednesday after comments from Federal Reserve Chair Janet Yellen signaled continued support for the economy, but the Nasdaq fell for a second session as momentum names sold off.
Financials and utilities were the day's biggest gainers, with the S&P financial sector index up 1.3 percent and the utilities sector index up 1.6 percent.
On the Nasdaq, Yahoo! Inc fell 6.6 percent to $34.07 after Alibaba Group filed for an initial public offering that valued the Chinese e-commerce company well below analysts' consensus estimate.
Analysts at BGC Partners and Atlantic Equities told Reuters that Alibaba's valuation disappointed some Yahoo investors. Yahoo holds a 22.6 percent stake in Alibaba, of which it must sell more than a third through the IPO.
"The Alibaba IPO is drawing money out of Internet stocks because investors have to raise capital for the Alibaba IPO. That's why we see pressure on names like Google, Facebook and Amazon today," said Tim Ghriskey, chief investment officer of Solaris Group in Bedford Hills, New York. Continuación...