Orders to U.S. factories for long-lasting manufactured goods rose in April by the most since January. But much of the strength came from a surge in the volatile category of commercial aircraft. A key category that tracks business investment fell for a third straight month, a sign that manufacturing remains under stress.

The Commerce Department says orders for durable goods increased 3.4 percent in April after a 1.9 percent gain in March. Demand in the closely watched category that serves as a proxy for business investment fell 0.8 percent after a 0.1 percent decline in March and a 2.1 percent plunge in February.

Manufacturing has been under pressure as weak global demand and a strong dollar hurt exports and falling oil prices have triggered cutbacks at energy companies.