* IBM slumps after results, drags down Dow, S&P 500
* Verizon, Travelers, United Tech up after results
* Yum Brands jumps on plans to spin off China business
* Harley Davidson down on cut to shipment forecast
* Indexes down: Dow 0.43 pct, S&P 0.25 pct, Nasdaq 0.28 pct (Updates to open)
By Abhiram Nandakumar
Oct 20 (Reuters) - U.S. stocks opened lower on Tuesday as IBM dragged down the Dow and S&P 500, a day after reporting disappointing results and cutting its full-year profit forecast.
IBM fell nearly 6 percent to $140.90 after it reported a bigger-than-expected fall in quarterly revenue.
The infotech sector was the biggest decliner among the 10 major S&P 500 sectors with a 0.6 percent fall.
Tech earnings gather steam as Yahoo and VMware report results after the close on Tuesday.
Third-quarter company earnings are in focus this week, with investors expecting tepid corporate performance and watching for outlook commentary to gauge the effects of a global economic slowdown on companies.
S&P 500 companies are expected to show a 3.9 percent fall in third-quarter profit.
Shares of Verizon were up less than 1 percent at $45.04 after the largest U.S. wireless service provider reported better-than-expected results.
Travelers rose 2.1 percent to $108.49 after the insurer's quarterly profit topped estimates, helped by higher underwriting gains.
At 9:44 a.m. ET (1344 GMT), the Dow Jones industrial average was down 74.83 points, or 0.43 percent, at 17,155.71, the S&P 500 was down 5 points, or 0.25 percent, at 2,028.66 and the Nasdaq composite index was down 13.82 points, or 0.28 percent, at 4,891.65.
Stock markets will likely be driven by sales performance and guidance around the measures companies are taking to grow revenue, said Mohannad Aama, managing director at Beam Capital Management in New York.
Of the S&P 500 companies that have reported until Friday, 43 percent have beaten expectations on revenue, according to Thomson Reuters data. About 60 percent companies on average beat sales estimates in a quarter.
U.S. stocks closed with slight gains on Monday as tech and biotech stocks advanced ahead of a heavy week of earnings.
Data on Tuesday showed U.S. housing starts rose 6.5 percent to a seasonally adjusted annual pace of 1.21 million units in September.
United Technologies rose 1.4 percent to $93.34 after the company's quarterly profit beat analyst expectations.
Harley Davidson fell 9.5 percent to $50.70 after the motorcycle maker cut its full-year shipment forecast.
Yum Brands rose 4.5 percent to $74.80 after the fast food group said it was preparing to separate its China business.
Sandisk jumped 6 percent to $76.41 after a Reuters report said Western Digital was in advanced talks to buy the memory chipmaker, citing people familiar with the matter.
Federal Reserve Chair Janet Yellen is scheduled to speak later in the day.
Declining issues outnumbered advancing ones on the NYSE by 1,512 to 1,159. On the Nasdaq, 1,279 issues fell and 907 advanced.
The S&P 500 index showed 14 new 52-week highs and three new lows, while the Nasdaq recorded 24 new highs and 15 new lows. (Reporting by Abhiram Nandakumar in Bengaluru; Editing by Don Sebastian)