MetroPCS Communications’ shares were down more than 7 percent today after the no-contract carrier reported third-quarter results. Shares in rival Leap Wireless International, which reports its results later today, also were down more than 6 percent.

MetroPCS ended the third quarter with just over 6.3 million subscribers, with 66,157 net additions in the quarter, disappointing analysts. In the year-ago quarter, the carrier had 249,265 net adds.

Metro’s ARPU was $41.08 in the third quarter compared with $40.73 in the year-ago quarter. Churn was 5.8 percent compared with 4.8 percent a year ago. Cost per growth addition was $153.94 compared with $128.21 a year ago.

Net income for the quarter increased $29 million, or 64 percent, compared to the third quarter of 2008. MetroPCS expects net subscriber additions in the range of 1 million to 1.2 million on a consolidated basis for the fourth quarter.

As for that persistent speculation that MetroPCS will hook up with Leap, Dow Jones reports that MetroPCS CEO Roger Linquist told analysts on a conference call that there’s no interest in pursuing a transaction, although he’s open to a deal if the opportunity arose.