Wholesale inventories rose 0.5% in May, while sales fell, the Commerce Department said Friday.
The increase followed a revised 0.2% increase in April, originally reported as a 0.4% gain.
Wholesale sales slipped 0.3%, the first decline in more than a year, after a 0.9% increase in April.
Economists had forecast inventories to rise 0.4%, Bloomberg reported.
Wholesale inventories account for about a fourth of total business stockpiles, while retailers and factories account for the rest.