The Dow Jones industrial average was down 21 points to 13,004 shortly before noon Monday.
The Standard and Poor's 500 was flat at 1,416. The Nasdaq composite rose 3 points to 3,013.
The Institute for Supply Management reported that U.S. manufacturing declined in November.
Businesses expressed concerns about the "fiscal cliff," a series of sharp government spending cuts and tax increases scheduled to start Jan. 1 unless an agreement is reached to cut the budget deficit.
Supervalu rose following a report that private equity firm Cerberus is considering options for buying parts of the struggling grocery store chain.