Private sector hiring unexpectedly contracted in June, payrolls processing firm ADP said Wednesday, in a possible sign that the economy may not be as sturdy as investors believe as they bid the S&P 50

The ADP employment report revealed that 33,000 nonfarm private jobs were unexpectedly lost in June, down from the 29,000 addition in May.

Economists had forecast an increase of 100,000 but declines in business services and education and health care offset increases in leisure and hospitality.