Stocks were poised for a lower open on Wednesday as weak data on the labor market became the latest in string of soft economic reports.

U.S. private employers added a scant 38,000 jobs in May, far below expectations and the lowest level since September 2010, a report by a payrolls processor ADP Employer Services showed on Wednesday.

Data Tuesday showing a drop in business activity in the U.S. Midwest added to other regional reports that have pointed to slower growth in manufacturing this month amid supply chain disruptions from the March earthquake and tsunami in Japan.

That bodes poorly for the Institute for Supply Management's manufacturing report, which is expected to slow, and casts a cloud ahead of a report on national employment on Friday.

The ISM monthly factory indicator, due at 10 a.m. EDT, is seen easing to 57.7 from the prior month's 60.4.

Construction spending for April is expected to show a rise of 0.3 percent after March's increase of 1.4 percent. The data is also due at 10 a.m. EDT. (1400 GMT)

It fits very neatly in with the puzzle we are putting together that speaks to another soft patch and really, a genuinely failed stimulus approach to growing the economy, said Peter Kenny, managing director at Knight Capital in Jersey City, New Jersey.

And it's not just about jobs. It's about manufacturing, it's about real estate, it's about consumer confidence. This is one data point in a very broad picture, and it's not encouraging.

S&P 500 futures lost 5.6 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 lost 43 points, and Nasdaq 100 futures fell 10.25 points.

Macy's Inc advanced 2.2 percent to $29.50 in premarket trade after the department store operator posted a 7.4 percent increase in May at stores open at least a year, beating analysts expectations.

Yahoo Inc dipped 1 percent to $16.38 premarket after two sources said it resolved a dispute with partner Alibaba Group over the Chinese company's transfer of its prized online payments unit to Chief Executive Jack Ma.

Sprint Nextel Corp asked U.S. regulators to block AT&T Inc's proposed $39 billion purchase of T-Mobile USA, saying the deal has no public interest benefit and would harm competition. Sprint lost 1.2 percent to $5.78, and AT&T Slipped 0.2 percent to $31.50 premarket.

(Reporting by Chuck Mikolajczak; editing by Jeffrey Benkoe)