You've probably seen a lot of headlines saying Affordable Care Act enrollment is going well. (In fact, I've written some of them.) But after yesterday's update, we should probably all recalibrate our math. And when we do, enrollment won't look so hot.

• We're two weeks into the ACA's fifth open enrollment period, and 1.5 million people have picked plans through HealthCare.gov.
• Two weeks into the last open enrollment period, just over 1 million people had picked plans through HealthCare.gov.
• That's the comparison folks have been making, and it does make enrollment seem stronger than last year.

Here's why that math is incomplete: Last year's open enrollment season was three months long. This one is half that, at six weeks. So, we're already a third of the way through this enrollment period.

• A third of the way through last year's enrollment season, more than 2.1 million people had signed up for coverage.
• The 1.5 million who have signed up so far this year doesn't look quite as good when you compare it that way — but that's the more accurate comparison, Avalere's Caroline Pearson says.
• By that measure, enrollment definitely isn't moving faster than last year — in fact, it's about 25% weaker.
• Twice as many people need to sign up each week to end up with the same totals when all is said and done. And that's not happening.

Yes, but: As Pearson notes, it's hard to make a direct comparison because there tends to be a surge at the end of the enrollment period. So it's hard to map out a clean trend line.

Still, given that the pace of sign-ups is already slipping, this year's last-minute surge would have to be enormous to close the gap. And it's hard to have an enormous surge without any official marketing or outreach encouraging people to sign up.

Republicans didn't argue among themselves too much when they decided to try to repeal the ACA's individual mandate through their tax overhaul. But that decision is nevertheless causing some issues for the broader tax effort.

• Sen. Susan Collins has said plainly she believes combining the two was a mistake. At a caucus lunch yesterday, she presented her GOP colleagues with an analysis that said repealing the mandate would counteract tax cuts for middle-class families.
• "My concern is what it might do to insurance premiums ... I've got a little bit of homework to do in understanding where that is, because I think that's key to this," Sen. Lisa Murkowski told my colleague Caitlin Owens.
• Sen. Ron Johnson became the first Republican to say he opposes the current bill (not because of the individual mandate). Reminder: If no Democrats get on board, three Republican defections would be enough to sink the bill.
• Bringing the ACA back into the mix has made it harder to pad that margin with even vulnerable moderate Democrats who might have otherwise been inclined to reach a deal on tax cuts.

Alexander-Murray probably won't be enough. Republican senators who support the tax overhaul all offered a similar refrain when I spoke to them yesterday: Whatever disruption is caused by repealing the individual mandate will be addressed by passing the ACA stabilization bill from Sens. Lamar Alexander and Patty Murray.

• "I think you have to do both. If you don't do both, people are going to get whacked really hard," Sen. Lindsey Graham said.
• Quick take: This is giving Alexander-Murray too much credit. Yes, it would stabilize insurance markets relative to where they are now. But it would do so by restoring the status quo that existed before last month. And before last month, repealing the individual mandate was still seen as an existential threat to the health of the ACA's exchanges.

Goldman Sachs sold more than half of its Community Health Systems stock in the last quarter, and the banking giant issued a dire report this week that basically suggested investors jump ship, Axios' Bob Herman reports.

What Goldman said: "We believe short-term fixes…may not help [CHS] solve longer-term problems." CHS is still saddled with $14 billion of debt, which Goldman thinks could lead to accounting audits or bankruptcy by next year. Goldman suggested CHS debt holders sell their 2020 bonds because more hospital sales will not "yield enough proceeds" to cover CHS' debt that is coming due.

Go deeper: Read more about the hospital chain's struggles here and here.

The Washington Post has a moving story this morning about a Northern Virginia family whose four-year-old daughter receives spinal tap and chemo treatments at Inova Fairfax Hospital.

Yes, but: Their old insurance carrier, Anthem, decided not to sell individual policies next year in their part of the state. Only Cigna is participating there — and Cigna's provider network doesn't include Inova Fairfax Hospital. It's the only local hospital with a dedicated pediatric cancer unit, according to the Post.

Reality check: The policy and political worlds often talk about "bare counties" and "market stability" in abstract terms. This is why they matter.