U.S. stock index futures dipped on Wednesday as a strong reading on the labor market failed to convince investors to add to gains a day after the Dow and S&P advanced to their highest close in about 2-1/2 years.

U.S. private employers added 187,000 jobs in January, more than forecast, according to a report from ADP Employer Services.

This suggests that the jobs momentum is going the right way, and it makes me more optimistic for Friday's payroll report. But it isn't such a blow-out number to allow us to add to gains, said Michael Yoshikami, president and chief investment strategist at YCMNET Advisors in Walnut Creek, California.

S&P 500 futures dropped 2 points and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures were off 11 points, and Nasdaq 100 futures fell 2.75 points.

Appliance maker Whirlpool Corp dropped 4.9 percent to $81.20 before the bell after its profit missed expectations.

Time Warner Inc rose 3.2 percent to $33.35 premarket after its profit topped estimates on a 21 percent jump in advertising sales at its cable networks.

Mattel Inc rose 1.4 percent to $24.49 premarket after its profit beat expectations on strong demand for its Barbie and American Girl dolls.

On Tuesday, the Dow and S&P 500 closed at their highest levels since June 2008 after strong earnings and signs of a surge in U.S. manufacturing. The Nasdaq surged almost 2 percent.

(Editing by Jeffrey Benkoe)