* IBM slumps after quarterly results
* Apple gains, earnings due after the close
* Dow down 0.09 pct, S&P up 0.68 pct, Nasdaq up 1.07 pct (Updates prices)
By Yasmeen Abutaleb
NEW YORK, Oct 20 (Reuters) - U.S. stocks were mixed on Monday as the S&P 500 and Nasdaq advanced, but disappointing results from IBM kept the Dow close to the unchanged mark.
IBM shares slumped 7.3 percent to $168.80 as the biggest drag on both the Dow and S&P 500 after third-quarter earnings fell well short of Wall Street expectations. IBM abandoned its 2015 operating earnings target and said it would pay Globalfoundries $1.5 billion over three years to take its loss-making semiconductor unit.
But earnings reports that exceeded analyst expectations, including Halliburton and Gannett Co., helped lift major indexes and ease the concerns over global growth and falling commodity prices that have gripped markets.
"Some of the concerns of last week have subsided," said Jack Ablin, chief investment officer at BMO Private Bank in Chicago.
"The more people just focus on the fundamental values and earnings and revenues and less on headlines, the more stocks have an opportunity to move higher."
At 2:57 p.m. the Dow Jones industrial average fell 14.36 points, or 0.09 percent, to 16,366.05, the S&P 500 gained 12.81 points, or 0.68 percent, to 1,899.57, and the Nasdaq Composite added 45.41 points, or 1.07 percent, to 4,303.85.
Earnings season will ramp up significantly this week with nearly 130 S&P 500 companies scheduled to report, including Apple Inc after the close Monday.
According to Thomson Reuters data through Monday morning, of 87 companies in the S&P 500 that have reported quarterly earnings, 63.2 percent have beat analyst expectations, roughly even with the 63 percent average since 1994 but below the 67 percent rate for the past four quarters.
Third-quarter earnings are expected to increase 6.7 percent from a year earlier on revenue growth of 3.6 percent.
The largest percentage gainer on the S&P 500 was Tesoro Corp, which rose 7.1 percent, while the largest percentage decliner was IBM.
The largest percentage gainer on the Nasdaq 100 was Celgene , up 4.6 percent, while the largest percentage decliner was Cisco Systems, down 1.7 percent.
Among the most active NYSE stocks were Bank of America , up 0.19 percent at $16.24; Petrobras, down 6.70 percent at $13.93, and Oi S.A., down 5.22 percent at $0.48.
On the Nasdaq, Apple, up 1.9 percent at $99.55 and Facebook, up 1.1 percent at $76.75, were among the most actively traded.
Advancing issues were outnumbering declining ones on the NYSE by 2,086 to 967, for a 2.16-to-1 ratio on the upside; on the Nasdaq, 1,611 issues rose and 1,030 fell for a 1.56-to-1 ratio favoring advancers.
The benchmark S&P 500 index was posting five new 52-week highs and two new lows; the Nasdaq Composite was recording 18 new highs and 33 new lows. (Editing by Bernadette Baum, Nick Zieminski and Peter Galloway)