Verizon slumped 3 percent after saying its earnings may "plateau" next year. Cablevision soared 16 percent after agreeing to be acquired by European cable company Altice.
The Dow Jones industrial average slipped 32 points, or 0.2 percent, to 16,706 in early trading.
The Standard & Poor's 500 fell three points, or 0.2 percent, to 1,991. The Nasdaq composite lost five points, or 0.1 percent, to 4,882.