* Symantec tumbles after CEO firing
* Tensions between Russia and U.S. still in focus
* Nike shares fall after results, Tiffany rises
* Indexes: Dow up 0.09 pct, S&P off 0.18 pct, Nasdaq down 0.87 pct (Updates to mid-afternoon, changes byline)
By Chuck Mikolajczak
NEW YORK, March 21 (Reuters) - U.S. stocks were little changed on Friday, as investors exercised caution heading into the weekend and early gains that pushed the S&P 500 to a record high evaporated.
The S&P 500 lost momentum after hitting an all-time intraday high of 1,883.97, with biotechs among the primary decliners. Biogen Idec Inc, down 8 percent to $319.14, and Gilead Sciences Inc, down 3.7 percent to $72.74, were the biggest drags on the S&P 500. The Nasdaq biotech index fell 3.5 percent.
The Dow and S&P 500 are still on track for their best weekly performance since mid-February.
"We are hitting our heads at the closing highs around the 1875 area. This is the area where you would find some resistance and that seems to be exactly what happened," said Ken Polcari, Director of the NYSE floor division at O'Neil Securities in New York.
"We hit resistance and didn't get through. They are just taking money off the table going into the weekend."
Investors continued to monitor geopolitical issues after President Vladimir Putin signed laws completing Russia's annexation of Crimea while Russia's MICEX stock index fell 1 percent after a U.S. decision to slap sanctions on Putin's inner circle.
Nike Inc fell 4 percent to $76.10 as the biggest drag on the Dow after it said late Thursday that growing pressures from weak emerging market currencies would take a toll on profit.
The Dow Jones industrial average rose 15.04 points or 0.09 percent, to 16,346.09, the S&P 500 lost 3.41 points or 0.18 percent, to 1,868.6 and the Nasdaq Composite dropped 37.614 points or 0.87 percent, to 4,281.671.
For the week, the Dow is up 1.8 percent, the S&P is up 1.6 percent and the Nasdaq is up 0.9 percent.
First Solar continued its recent meteoric rise, climbing 4.1 percent on Friday, its sixth straight daily increase. The stock has jumped 38 percent over that period.
Symantec Corp shares weighed on the Nasdaq, tumbling 12.7 percent to $18.25 a day after it fired Chief Executive Steve Bennett, the second time it has sacked its top executive in less than two years.
Despite recent market strength, trading volume has been anemic on positive market days, suggesting limited conviction behind the move. However, volume is expected to surge on Friday as options expire alongside multiple index rebalances. Credit Suisse estimates $14 billion in gross trading from the S&P 500 index rebalance, with another $6 billion from rebalancing in other indexes.
In earnings news, Tiffany & Co reported adjusted fourth-quarter earnings and gave a profit outlook that were below estimates. However, shares rose 1 percent to $92.08.
Darden Restaurants Inc reported results largely in line with expectations and affirmed its plan to divest its Red Lobster business. Shares rose 2.6 percent to $50.56.
The U.S. Federal Reserve late Thursday said big U.S. banks have enough capital buffers to withstand a drastic economic downturn. The central bank said 29 of 30 major banks met the minimum hurdle in its annual health check.
The only bank to fall under the 5 percent requirement for top-tier capital was Zion Bancorp, which said it would resubmit a capital plan to the Fed. Shares of Zion fell 5.2 percent to $31.27.
(Editing by Chizu Nomiyama and Nick Zieminski)