Inventories at U.S. wholesalers rose 0.8 percent in April, double Wall Street expectations, as automotive stocks swelled, government data showed on Wednesday.

The Commerce Department (search) also revised up its March wholesale inventory (search) advance to 0.6 percent, from an originally reported 0.4 percent gain. Economists polled by Reuters had forecast a 0.4 percent April inventory rise.

Rising inventories can signal either growing business confidence about future demand or an unexpected sales drop that causes unsold stocks to pile up.

Stocks of durable goods (search) — products meant to last three years or more — rose 0.4 percent in April after a 0.2 percent advance in March.

Auto inventories rose 1.5 percent in April, reversing direction after a 2.2 percent decline the month before. Professional equipment stocks rose 1.4 percent and computer equipment inventories rose 0.1 percent.

Wholesale sales rose a hearty 1.5 percent in April, their fastest rate in more than year, after a more modest 0.2 percent growth the month before. Auto sales fell 2.5 percent after a 1.2 percent decline in March.