By major insurance company, we are referring to the number of subscribers and providers each company has.  With insurance companies, size does matter.  A smaller company (fewer people on the books), can be significantly impacted by a bad year of claims.  Larger companies can better weather the bad years.  We have seen many times where a new carrier comes into the state, drops rates to capture the market and then due to the resulting claims (a few years behind), sells off their "block of business" or pulls out all together.  This is especially true lately with national players and smaller players.  You don't want to have health problems when your company is leaving...the other carriers will not pick you up.  Stability is crucial and size helps.