Energy shares lifted the S&P 500, while the Dow and Nasdaq remained little changed as investors await the outcome of a two-day meeting of the U.S. Federal Reserve.
U.S. stocks had opened slightly higher, with the Dow briefly crossing the 18,000 mark, as oil prices rose 2.9 percent due to a weaker dollar and hopes for an easing of the oil glut.
Oil majors Exxon and Chevron were up about 1 percent and gave the biggest boost to the S&P 500.
Markets see no chance of an interest rate increase at the meeting that is set to begin on Tuesday but have priced in a one-in-five chance of a hike at the meeting in June. Fed officials have repeatedly said a hike in June is on the cards.
While job growth continues to gain strength, inflation stubbornly remains below the Fed's 2 percent target.
"Investors are focused on the Fed's language and especially their statements of the global and economic developments and to what degree those items pose risks," said Bill Merz, investment strategist at U.S. Bank.
Investors will also assess earnings reports from major players such as Apple, AT&T and Ebay, which are due to report after the market close.
First-quarter earnings from S&P 500 components are expected to have fallen 7.3 percent from a year earlier, according to Thomson Reuters I/B/E/S. Of the 135 companies that have reported, 59 percent reported revenue above analyst expectations, just short of the average 60 percent since 2002.
"Expectations are low and while companies are modestly beating them, the returns over the past couple of months have been due to multiple expansions and not fundamental growth and current prices are slightly high," said Merz.
With the S&P 500 up in eight of the past 10 weeks and nearing the record high set almost a year ago, traders are struggling to find reasons to push it even higher as underwhelming earnings and the specter of higher interest rates hover over markets.
At 12:43 a.m. ET (1643 GMT) the Dow Jones industrial average was up 15 points, or 0.08 percent, at 17,992.24, the S&P 500 was up 3.57 points, or 0.17 percent, at 2,091.36 and the Nasdaq Composite was down 4.46 points, or 0.09 percent, at 4,891.33.
Six of the 10 major S&P sectors were higher, with the energy index's 1.18 percent rise leading the advancers.
Orders for long-lasting U.S. manufactured goods rebounded less than expected in March. The Commerce Department said on Tuesday that orders for durable goods increased 0.8 percent last month, below the 1.8 percent rise expected by economists polled by Reuters.
Adding to the day's pressure, the consumer confidence index fell to 94.2 in April and came in below expectations.
Shares of Apple were down 0.4 percent at $104.63. The world's largest public company is expected to report a fall in quarterly revenue on weakened demand for its smartphones.
DuPont rose 2.5 percent to $67.59 after it said it is aiming to buy back $2 billion shares this year.
Dow components 3M and Procter & Gamble were down about 1.5 percent, after reporting a fall in sales.
Advancing issues outnumbered decliners on the NYSE by 2,216 to 691. On the Nasdaq, 1,684 issues rose and 1,021 fell.
The S&P 500 index showed 17 new 52-week highs and 1 new low, while the Nasdaq recorded 45 new highs and 20 new lows. (Reporting by Tanya Agrawal; Editing by Don Sebastian)