* Yellen: Risks "moderated, not elevated"; no bubbles forming
* Private employers add fewest jobs since Jan 2014
* Tech stocks weigh; energy stocks shed most gains
* Indexes down: Dow 0.7 pct, S&P 0.6 pct, Nasdaq 0.6 pct (Updates to early afternoon)
By Tanya Agrawal
May 6 (Reuters) - U.S. stocks were lower in early afternoon trading on Wednesday after a triple whammy of a pullback in energy stocks, weak jobs data and Janet Yellen's comment that equity valuations are "generally quite high".
Wall Street had opened higher, but reversed course early in the session after the U.S. Federal Reserve chair's comments in what has been a typically choppy trading session.
Yellen described risks to financial stability as "moderated, not elevated" and said she does not see any bubbles forming.
The S&P 500 closed above its record high late last month, while the Nasdaq was in striking distance of its record high. But mixed data has since pulled the indexes from those highs.
"Even if equity markets are overvalued, they are not terribly over extended," said Tim Dreiling, a senior portfolio manager at U.S. Bank Wealth Management, which oversees $128 billion.
The S&P 500 currently trades at 16.8 times forward earnings, higher than its 10-year median of 14.7, according to Thomson Reuters StarMine.
At 13:41 p.m. EDT (1741 GMT) the Dow Jones industrial average was down 124.99 points, or 0.7 percent, at 17,803.21, the S&P 500 was down 12.66 points, or 0.61 percent, at 2,076.8 and the Nasdaq Composite was down 30.56 points, or 0.62 percent, at 4,908.77.
U.S. private employers added 169,000 jobs last month, the fewest since January 2014 and far below economists' estimates, posing a downside risk for the more comprehensive nonfarm payrolls report due on Friday.
"If the Friday numbers come in weak, it certainly makes more improbable that we'll have a June lift-off, and then maybe calls into question what happens in September," said Dreiling.
Adding to the weak jobs data, applications for U.S. home mortgages fell last week, while nonfarm productivity fell in the first quarter.
U.S. Treasuries continued to slide for a ninth straight day amid a global bond sell-off, with longer-maturity Treasuries declining the most.
The utilities index was the biggest loser among the 10 major S&P sectors. The energy index erased most of their earlier gains to trade up 0.1 percent.
Tech stocks, led by Apple and Microsoft, were the biggest drag on the three major indices. Apple has fallen for three straight sessions.
MoneyGram gave up some of its earlier gains after Western Union said it was not in talks to buy the company. MoneyGram was up 18.4 percent at $9.25, while Western Union was up 3.2 percent at $21.63.
Herbalife jumped 20.1 percent to $48.16 after it raised its full-year profit forecast.
Synageva BioPharma more than doubled to hit a record high of $215.98 after Alexion offered to buy the company. Alexion was down 9.9 percent at $151.75.
Declining issues outnumbered advancing ones on the NYSE by 2,221 to 819, for a 2.71-to-1 ratio on the downside; on the Nasdaq, 1,607 issues fell and 1,066 advanced for a 1.51-to-1 ratio favoring decliners.
The benchmark S&P 500 index was posting 5 new 52-week highs and 5 new lows; the Nasdaq Composite was recording 25 new highs and 62 new lows. (Editing by Savio D'Souza)