BZZZZZZT: Your time is up. Today was the deadline for carriers to decide whether they're in or out for OE4
Lots of healthcare reporters, pundits, executives, providers and politicians are likely issuing a huge sigh of relief at this moment, because after month after month of various insurance carriers announcing that they're dropping off the ACA exchange in certain counties only, state-wide or even dropping out of the individual market entirely (or that they're going out of business altogether, as in the case of four more co-ops), today was the deadline for carriers to officially commit to participating in the 2017 Open Enrollment Period starting on November 1st.
Now, it's important to note that this may only refer to the 39 states which will be operating on the federal exchange (HealthCare.Gov). This was 38 last year, but Kentucky's "kynect" exchange had the plug pulled for no reason whatsoever by GOP Governor Matt Bevin last winter, so they'll be joining the mothership this year as well. That leaves 11 states (+DC) running their own full exchange platform; those states may have different signing deadlines.
In any event, the only major last-minute news I'm aware of today is in Nebraska, where Blue Cross Blue Shield decided to drop out at the (literal) last minute, and Pennsylvania, where Highmark (which many were afraid was also going to drop out) announced that they'll be sticking around for at least another year.
There may be some more last-minute surprises to come--bear in mind that last year, news about several of the co-ops failing didn't actually hit the news until sometime in October--but this should lock in just which carriers will and will not be participating for 2017.
Assuming no one else bails (or "suspends additional enrollment" partway through the period, which also happened a couple of times last year), the official tally of participating carriers should be set as of now.