An analysis from the Kaiser Family Foundation (KFF) provides a state-by-state look at where United is participating in the exchanges this year, providing context for what the effect would be if it withdraws from some or all remaining markets. United participates in 1855 counties (59% of all counties nationwide and an estimated 71% of marketplace enrollees). In 29% of counties, its exit would result in a drop from two insurers to one. In another 29% of counties, there would be two exchange insurers as a result of a withdrawal. If United were to leave the exchange market overall, 1.8 million Marketplace enrollees would be left with two insurers, and another 1.1 million would be left with one insurer as a result of the withdrawal.
The analysis can be accessed at http://kff.org/health-reform/issue-brief/analysis-of-unitedhealth-groups-premiums-and-participation-in-aca-marketplaces/.