Much is being made of the rapid demise of ACA CO-OP plans. Several more closures at the end of this year were recently announced. Of the 23 original plans, 9 will not be around in 2016 and a number more are endangered.

Two lists regarding CO-OPs have recently been posted on healthsprocket:
Top Five Health CO-OPs by 2015 Estimated Enrollment
Nine Health CO-OPs Are Ceasing Business in 2015

MCOL research indicates that CO-OPs collectively serve an estimated 934,400 members in 2015, up from 435,223 members at the end of 2014. 478,000 (51%) of the 2015 members are with plans that are closing.