US STOCKS-Wall St flat ahead of Yellen; biotechs bounce

(Fixes spelling error in headline)

* Dow Chemical to spin off unit, merge it with Olin (NYSE: OLN - news)

* Healthcare buoys indexes as biotechs bounce back

* Fed Chair Janet Yellen to speak shortly before the closing bell

* Indexes up: Dow 0.01 pct, S&P 0.08 pct, Nasdaq 0.23 pct

By Chuck Mikolajczak

NEW YORK, March 27 (Reuters) - U.S. stocks held near the unchanged mark on Friday, putting major indexes on track to barely snap a four-session losing streak, ahead of a speech by Federal Reserve Chair Janet Yellen that could create a volatile close on Wall Street.

Healthcare stocks helped buoy indexes with biotech stocks bounced 2.3 percent higher after suffering a 7-percent drop in the prior four sessions, while energy was the worst performing S&P sector as crude prices resumed their decline.

"We've seen a pretty sharp selloff in biotech. What we've done is bounce down to the low end of the recent range set on March 11 and it looks like the market is trying to find some stability here," said Tim Ghriskey, chief investment officer of Solaris Group in Bedford Hills, New York.

Fed Chair Yellen will speak on monetary policy in San Francisco, just 15 minutes before the closing bell (1945 GMT), and traders will keep an ear out for clues on the timing of the start of the tightening path at the Fed.

"Everything has been said by the Fed, but anytime it is said again, it causes some reaction," said Ghriskey.

Investors have been cautious ahead of the start of earnings season, as traders look to see how much the greenback's strength will hurt corporations' bottom lines.

The Dow Jones industrial average rose 1.74 points, or 0.01 percent, to 17,679.97, the S&P 500 gained 1.69 points, or 0.08 percent, to 2,057.84 and the Nasdaq Composite added 11.32 points, or 0.23 percent, to 4,874.68.

Dow Chemical shares rose 3.9 percent to $48.26 after it announced the spinoff of part of a unit that will then merge with Olin Corp. Olin shares soared 21 percent to $32.90.

BlackBerry posted a fiscal fourth-quarter profit, its turnaround efforts beginning to gain traction. U.S.-listed BlackBerry shares were up 2.3 percent at $9.52 in volatile trading.

U.S. consumer sentiment fell month-over-month in March, a survey released on Friday showed, though the decline was smaller than forecast.

The final reading on gross domestic product for the last quarter of 2014 was unchanged from the previous forecast, at a 2.2 percent rate of expansion. After-tax corporate profits fell at a 1.6 percent rate in the fourth quarter as a strong dollar dented the earnings of multinationals.

Advancing issues outnumbered declining ones on the NYSE by 1,710 to 1,222, for a 1.40-to-1 ratio; on the Nasdaq, 1,335 issues rose and 1,233 fell, for a 1.08-to-1 ratio favoring advancers.

The S&P 500 index posted 4 new 52-week highs and 6 new lows; the Nasdaq Composite recorded 20 new highs and 35 new lows.

(Editing by Chizu Nomiyama and Nick Zieminski)