Comcast Corp. shares fell as much as 9.9% to their lowest in more than two years after the company reported fourth-quarter revenue and profit that beat Wall Street’s expectations but subscriber losses in its broadband unit raised concerns among investors.

Comcast Corp.’s stock fell 1.9% early Thursday, after the cable company’s fourth-quarter earnings topped estimates but it continued to shed subscribers at its domestic broadband business. The company had per-share earnings of $1.