WASHINGTON (AP) — Orders to U.S. factories fell in July by the sharpest amount in four months, held back by weaker demand for commercial aircraft and heavy machinery. A key category that reflects business investment plans also fell.

The Commerce Department says factory orders dropped 2.4 percent in July compared with June, when orders rose 1.6 percent.

Orders for core capital goods, a category viewed as a proxy for business investment spending, fell 4 percent, the biggest setback since February.

Core capital goods are considered a good measure of businesses' confidence in the economy. They include items that point to expansion — such as machinery, computers and heavy trucks — while excluding volatile orders for aircraft and defense. The July setback was expected to be temporary.

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