Stock index futures pointed to a lower open for Wall Street on Wednesday, as disappointing earnings results, including Pfizer, offset a report showing fewer-than-expected private sector job losses in January.

Pfizer Inc
shares fell more than 2 percent to $18.82 in premarketing trading and weighed on the overall market after the world's biggest drugmaker said quarterly earnings rose but missed estimates and forecast full-year profit below expectations.

Fashion company Polo Ralph Lauren Corp reported higher quarterly income and strengthened its revenue outlook. Still, its shares fell 6.6 percent to $79.95 premarket.

Some people are taking a selling opportunity on a pocket of disappointment from select names on the S&P 500, said Craig Peckham, equity trading strategist at Jefferies & Co in New York.

S&P 500 futures fell 3.9 points and were below 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 dropped 11 points, and Nasdaq 100 futures lost 4.75 points.

A report by ADP Employer Services showed the pace of U.S. job losses in the private sector slowed in January, as employers reported the smallest payroll decline in nearly two years.

From a macro standpoint, anything is going to be little more than a setup for non-farm figure on Friday, Peckham said.

The closely watched government jobs report due Friday is expected to show continued improvement in U.S. employment.

Peckham said ADP has understated the overall trend in employment recently, and investors will watch the employment component of the Institute for Supply Management (ISM) services report due later Wednesday.

The ISM will release its January non-manufacturing index at 10 a.m. (1500 GMT). Economists look for a reading of 51.0, indicating an expansion in the services sector, versus 49.8 in December.

The S&P 500 fell more than 6 percent in the last three weeks of January, even as some sector bellwethers, including Microsoft Corp , reported strong earnings.

(Editing by Jeffrey Benkoe)