Tenet Healthcare plunged after the hospital operator said its third-quarter profit fell as its absorbed costs associated with its acquisition of Vanguard Health Systems. Delphi Automotive dropped after the company cut its earnings forecast for the year.
The Standard & Poor's 500 index was down three points, or 0.2 per cent, to 1,764 as of noon (1700 GMT) Tuesday.
The Dow Jones industrial average was down 20 points, or 0.1 per cent, to 15,619 points.
The Nasdaq composite fell point to 3,935.
The market is still close to record levels after a surge that has put the S&P 500 on track for its best performance since 2009. The index is up 24 per cent this year.