AT&T carried the most Internet traffic from businesses across the U.S., while the five largest U.S. Internet service providers (ISPs) accounted for nearly 50% of total U.S. business Internet traffic in September, according to a comScore report. That figure rises to 70% for large enterprise businesses.

AT&T carried 20% of all browser-based Internet page views, followed by Verizon (12%) and CenturyLink-Qwest (7%). Comcast, Level 3 and TW Telecom each accounted for 5% of U.S. business Internet traffic in September, while Sprint, Time Warner Cable and Cogent carried 4%. Cox accounted for 3%.

AT&T carried the most Internet traffic across all sizes of U.S. businesses – small, medium and large. While the five largest ISPs accounted for 70% of traffic from large businesses, they accounted for 56% of medium-sized business traffic and 40% of small business Internet traffic.

Also indicative of greater competition in the small business market segment, ISPs outside the top ten accounted for nearly 40% of small-business Internet traffic, with AT&T capturing a 13% share. Comcast and Verizon ranked second and third in the small business segment, with 8% and 7% market shares, respectively.

Despite the high concentration of market power in the business ISP market, concentration in the residential ISP market is even greater, noted Greg Mishkin, comScore vice president of telecom and wireless, in a news release.

“The current state of the domestic business ISP market reveals a landscape led by a couple of top providers. However, even with smaller carriers contributing only a fraction of the traffic delivered by top carriers, the business ISP market is still more competitive than the residential ISP market,” he said.

“The small business segment is even more competitive among ISPs, highlighting the need for providers to develop strong marketing strategies to ensure they can retain and grow market share.”

 Geography and by Industry Rankings

Breaking out results geographically, comScore found that AT&T also held the top position in the majority of the largest local ISP markets. AT&T was the leading carrier for overall traffic in 7 of the 10 largest U.S. business Internet markets surveyed in September. Verizon ranked highest in the other three – New York, Boston and Washington D.C.

Local market business Internet traffic market share broke out the same way in the large-sized market segment, where AT&T carried the most Internet traffic in 7 of 10, while Verizon ranked highest in New York, Boston and San Francisco.

Cable ISPs made their first top showings in the local small business segment, where Comcast and AT&T captured the highest share of traffic in four of the largest local markets each. Cablevision ranked highest in New York, while Verizon came out on top in Washington D.C.

Examining the results across industry sectors, AT&T carried approximately 30% of traffic in the ‘Health Care and Medical’ and Financial Services industries, a “notable lead,” comScore commented.

In contrast, the Telecommunications and ‘Software and Technology’ markets is much more fragmented, with the leading carriers accounting for less than 20% of Internet traffic, followed closely by competitors.