Yesterday, Senator Elizabeth Warren (D-MA) aggressively questioned Treasury Secretary Jack Lew about efforts to break up so-called “too big to fail” banks. She noted that under the previous Treasury Secretary, the administration failed to support a Senate amendment to break up these banks.

She then probed Lew about if he would support such efforts.

LEW: I think we’re on a path now which is the right path, which is to implement Dodd-Frank and then to take stock when we’re done implementing Dodd-Frank. […]

WARREN: Ai??The question is though, Secretary Lew, this is about concentration. We all said back in 2009, 2009, the problem that caused the financial crash in part was concentration in the banking industry. And what do we see now? We see more concentration. […] How big do the biggest banks have to get before we consider breaking them up? They’re thirty percent larger now than they were five years ago. Do they have to double in size? Triple in size? Quadruple in size, before we talk about breaking up the biggest financial institutions? […]

LEW: There are many things going on and I’m not trying to avoid addressing the question of “too big to fail,” I’m trying to address quite clearly that that’s an unacceptable policy. But I think we have to take in account all the factors that together add up to systemic risk.

WARREN: Fair enough, Mr. Lew, Secretary Lew. But I really think the evidence suggests that concentration is one of those factors. And that when we see the largest financial institutions getting bigger and bigger, it tells us we are not clearly on the path to resolving “too big to fail.”