GAO reviewed the small group health insurance market to identify the number of licensed carriers, the largest carriers, and their market share in each state. GAO found that (1) the median number of licensed carriers in the small group market per state was 28, (2) the median market share of the largest carrier was about 33 percent, (3) the five largest carriers, when combined, represented three-quarters or more of the market in 19 of the 34 states reviewed and they represented more than 90 percent in seven states, (4) 25 of 37 states identified Blue Cross and Blue Shield (BCBS) carrier as the largest carrier offering health insurance in the small group market, and (5) the median market share of all the BCBS carriers in the 34 states supplying information was about 34 percent.