Elizabeth Warren just destroyed Federal Reserve Chair Janet Yellen over JPMorgan's "living will."

In the Dodd-Frank Act, there is a provision, known as a living will, that must describe a company's strategy for, "rapid and orderly resolution in the event of material financial distress or failure of the company."

This provision comes out of the Lehman Brothers bankruptcy, which triggered the financial crisis and took three years to resolve.

Warren has some concerns regarding JPMorgan's living will, which she notes has been approved each of the last years.

Compared to JPMorgan, Warren said Lehman was "tiny."

Warren noted that at the time of its bankruptcy, Lehman had $639 billion in assets; today, JPMorgan has nearly $2.5 trillion in assets.

Warren also said that Lehman had 209 subsidiaries when it failed; today, JPMorgan has 3,391 subsidiaries, or more than 15 times the number Lehman had when it went under.

Before delivering the stat about how many subsidiaries JPMorgan has, Warren said, "I almost couldn't believe this when I read it."

In response, Yellen said the Fed is continuing to work with firms to give them feedback regarding their plans, a response Warren wasn't thrilled with, asking Yellen, "[Has JPMorgan] ever gotten to a plan, which you can stay with a straight face, is credible?"

Yellen's response: "I've understood this to be a process, these are extremely complex documents to produce. In our second round of submission, we're looking at plans that run into tens of thousands of pages."

This didn't really cut it with Warren either. As the most junior member of the Senate Banking Committee, Warren asked Yellen questions last, and was left to conclude with:

"I think the language in the [Dodd-Frank] statute is pretty clear. That you are required, that the Fed is required to call it every year on whether these institutions have a credible plan. And I remind you, there are vey effective tools that you can use if those plans are not credible. Including, forcing these financial institutions to simplify their structure, or forcing them to liquidate some of their assets. In other words, break them up."

Warren has long been critical of Wall Street and particularly of the size of big banks.

Following nearly two hours of questions that danced around the issues we hear all the time such as: when will the taper end, when will rates rise, what's the deal with the labor market, Warren finished the proceedings with a pointed question regarding a specific provision in Dodd-Frank.

Our guess is that Yellen wasn't too upset the hearing ended when it did.

Here's the relevant seven-minute clip from C-SPAN, which is well worth watching.