* S&P, Dow on pace for best 1st qtr since 2013
* Utilities lead S&P sectors; energy lags
* Dow down 0.13 pct, S&P up 0.03 pct, Nasdaq up 0.17 pct (Updates to early afternoon)
By Yashaswini Swamynathan
March 31 (Reuters) - Gains in Amazon kept the S&P 500 and the Nasdaq in the positive territory on Friday, while a drop in Exxon weighed on the Dow as investors assessed their positions at the end of a strong quarter.
U.S. stocks have hit a series of record highs following the election of President Donald Trump on bets that he would introduce tax cuts and boost infrastructure spending. The rally has also benefited from a raft of robust economic data.
The S&P is on track to gain 5.7 percent and the Dow 4.7 percent for the quarter ending Friday, their biggest first-quarter gains in four years.
Investors are looking to the upcoming earnings season to justify lofty valuations on Wall Street.
First-quarter earnings for S&P 500 companies are expected to rise 10.1 percent, according to Thomson Reuters I/B/E/S. The index is trading at about 18 times earnings estimates for the next 12 months against its long-term average of 15.
"If earnings reports come in as expected, then they will catch up with the valuations, if they don't then I think the market will start to pull back," said Randy Frederick, vice president of trading and derivatives at Charles Schwab & Co Inc.
At 12:29 p.m. ET (1629 GMT), the Dow Jones Industrial Average was down 25.97 points, or 0.13 percent, at 20,702.52; the S&P 500 was up 0.73 points, or 0.03 percent, at 2,368.79 and the Nasdaq Composite was up 10.22 points, or 0.17 percent, at 5,924.57.
Five of the 11 major S&P sectors were higher, led by the defensive utilities. Energy lagged with a 0.42 percent decline, while the rest were little changed.
A 2 percent drop in Exxon Mobil's shares caused the Dow to dip slightly.
FMC Corp were the biggest gainers on the S&P, up 13.5 percent after the company agreed to buy DuPont's crop protection business and sell its health and nutrition unit to DuPont. DuPont's shares were down about 1 percent
Amazon.com was the top stock on the S&P and the Nasdaq, with a 1.4 percent gain.
Advancing issues outnumbered decliners on the NYSE by 1,804 to 1,010. On the Nasdaq, 1,638 issues rose and 1,100 fell.
The S&P 500 index showed 15 52-week highs and one low, while the Nasdaq recorded 72 highs and 14 lows. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Anil D'Silva)