Caterpillar said Wednesday that its earnings fell 43 percent in the second quarter as China's economy slowed and commodity prices sank.
Apple rose after beating analysts' estimates for quarterly earnings.
The Dow Jones industrial average fell 25 points, or 0.2 percent, to close at 15,542.
The Standard & Poor's 500 index fell six points, or 0.4 percent, to 1,685.
The technology-heavy Nasdaq composite index edged up a fraction to 3,579.
AT&T fell after its costs surged in the latest quarter. The company spent heavily on subsidizing smartphone sales.
Three stocks fell for every one that rose on the New York Stock Exchange. Volume was average at 3.3 billion shares.