Broadband customer gains by the nation’s largest cable and telephone companies in the second quarter of 2011 were the second fewest of any quarter in the last 10 years, according to data released late last week from Leichtman Research Group.

LRG’s research tracks the nation’s 18 largest cable and telephone providers, which represent about 93% of the broadband market. According to that research, those providers collectively gained about 350,000 net additional high-speed Internet service customers during second quarter of 2011. Over the past year, the 18 broadband providers have added 3.3 million subscribers, about 91% of the net additions over the prior year.

In an announcement of the findings, LRG President and Principal Analyst Bruce Leichtman did not speculate on the cause of the slower growth, other than noting that “the second quarter is traditionally the slowest of the year for industry growth.” Leichtman added that although new subscribers in 2Q 2011 were 900,000 less than in 1Q 2011, they were slightly higher than last year’s second quarter.

The majority (77%) of the net 350,000 new subscribers went to the cable companies, while the top seven telcos gained just over 80,000 net new customers. But the net new customer numbers tell only part of the story, as the nation’s two largest telcos—AT&T and Verizon–have seen a significant shift in their broadband mix.

AT&T and Verizon added 628,000 fiber subscribers in the quarter while having a net loss of 578,000 DSL subscribers for a net gain of 50,000 subscribers. While Verizon gained 62,000 net new broadband customers, AT&T saw a net customer loss of 12,000 during the same period.

Previous LRG research for 2010 also showed slow telco net broadband customer growth dragging down overall broadband subscriber growth.

Other key findings of the new LRG research released last week:

  • The top phone companies added about 80,000 subscribers during the quarter—compared to a net loss of 10,000 subscribers in 2Q 2010.
  • The top cable companies added more than 270,000 broadband subscribers in the quarter—about 81% of the additions during the same quarter a year ago.
  • The top cable broadband providers have a 56% share of the overall market, with 8.9 million more subscribers than the top telephone companies