U.S. chain store sales slipped in July, a report Tuesday showed, as consumers wary of a shaky economic rebound kept a tight hold on their wallets.

Instinet's Redbook Retail Sales Average fell 0.4 percent in the four weeks ended Aug. 3 compared with the same period in the previous month.

"A majority of reporting companies ended July below plan," the report said.

The Redbook Average is compiled from a sample of general merchandise retailers representing about 9,000 stores. Same-store sales measure revenue at stores open at least a year.

The index is released weekly by Instinet Research, a division of Instinet Group Inc. , an electronic brokerage that is an affiliate of Reuters Group Plc .