America’s largest banks are still too big to fail, but Jamie Dimon’s JPMorgan Chase is especially dangerous.

Don’t take my word for it. This stark warning appears in a joint Federal Reserve - FDIC “feedback letter” sent to JPM on its latest Resolution Plan, a kind of “living will” that large banks must file.

In theory, the resolution plans assure the banks can stage an orderly liquidation if events render them insolvent. The goal is to avoid another 2008-style Lehman Brothers meltdown.

Difficult? Yes, but not impossible. Citigroup passed while Goldman Sachs (GS) and Morgan Stanley (MS) earned partial passing grades.

Unfortunately, the good news ends there.

JPMorgan Chase failed, as did Bank of America (BAC), Wells Fargo (WFC), State Street (STT) and Bank of New York Mellon (BK).

Shame on all of them, but what’s odd here is that JPMorgan Chase failed differently.

All the feedback letters have a “Legal Entity Rationalization” section. It deals with corporate structural issues that might impede an orderly wind-down.

In that section of JPMorgan Chase’s feedback letter, the Fed and FDIC said the bank should “mitigate risks that, if not overcome, could otherwise undermine successful execution of the preferred strategy and, more broadly, pose serious adverse effects to the financial stability of the United States.”

Read that again and let it sink in.

The Fed didn’t say this to Bank of America, Wells Fargo or the others.

These unspecified risks apparently exist only at JPMorgan Chase.

So, it looks like something about JPMorgan Chase is so uniquely dangerous that it could harm “the financial stability of the United States.”

(Don’t believe me? Read the official press release yourself. At the bottom you’ll see links to each bank’s feedback letter. The statement above is on page 11 of the JPM letter.)

Back in 2014, I wrote about Janet Yellen’s cavalier attitude that left banks still vulnerable to crisis collapse. She’s clearly awake now. Fed chairs use such language only after very serious, high-level consultation.

How high level?

Two days before the Fed released the feedback letters, Janet Yellen had a short-notice private meeting with President Obama and Vice President Biden.

The White House said they discussed, among other things, “potential risks to the economy, both in the United States and globally.” Does Yellen think JPMorgan Chase is one such risk?

I don’t know, but it’s certainly fair to wonder when we see such dire language.

It’s also fair to wonder why the Fed and FDIC aren’t moving more aggressively to control this mysterious risk. The nation’s financial stability is in peril, and their only visible response is to send JPM a strongly worded letter?

Maybe that’s all Obama would allow. We saw last year how his administration changed the rules to protect JPM and other convicted-felon banks from losing business.

Alternately, maybe the Fed and FDIC are quietly working to force change at JPM. We should all hope so.

If JPMorgan Chase collapses like Lehman Brothers did, no one will escape unharmed.

Patrick Watson is an Austin-based financial writer. Follow him on Twitter @PatrickW