AT&T continues lead U.S. carriers in a key Ethernet ranking.

Vertical Systems Group on Thursday released its latest U.S. Carrier Ethernet leaderboard, ranking the companies that have the most retail port share. A company must have at least 4 percent share to make the list.

AT&T leads the list, followed by Level 3 Communications. Both companies have been one-two in the rankings since 2014.

The list didn’t change at all from the 2016 mid-year rankings, except for Windstream leapfrogging Cox from ninth to eighth place. Altice USA and Sprint joined the “challenger tier” (companies with between 1 and 4 percent share) alongside Cogent and Zayo.

Rick Malone, principal at Vertical Systems Group, said growth in the Ethernet market “softened” in the second half of 2016. The average rate of growth for the year was 16 percent. It was more than 20 percent in 2015.

“This easing is expected to continue as alternative technology solutions are evaluated, such as dark fiber and SD-WAN,” said Malone.

Charter Communications was sitting at third place on the 2016 mid-year leaderboard and remains in that position after acquiring Time Warner Cable and Bright House Networks for approximately $71 billion.{ad}

“M&A activity is accelerating as Ethernet providers scramble to extend fiber footprints, enhance service technology and enter new markets,” Malone said. “Looking forward, the Leaderboard will undergo dramatic changes as a result of these transactions.”