They got themselves into this mess, they should certainly get themselves out:

Several of the world’s biggest banks are in talks to put up about $75 billion in a backup fund that could be used to buy risky mortgage securities and other assets, a move designed to ease pressure on a crucial part of the credit markets that threatens the broader economy.

Citigroup, Bank of America and JPMorgan Chase, along with several other financial institutions, have been meeting to come up with a plan to create a fund that could prevent a sharp sell-off in securities owned by bank-affiliated investment vehicles. The meetings, which began three weeks ago, have been orchestrated by senior officials at the Treasury Department, and the discussions have intensified in the last few days.

UPDATE: From Pragmatic Realist in the comments:

from “Only Yesterday: a History of the 1920’s” by Frederick Allen:

A few minutes after noon, some of the more alert members of a crowd which had collected on the street outside the Stock Exchange, expecting they knew not what, recognized Charles E. Mitchell, erstwhile defender of the bull market, slipping quietly into the offices of J. P. Morgan & Company on the opposite corner. It was scarcely more than nine years since the House of Morgan had been pitted with the shrapnel-fire of the Wall Street explosion; now its occupants faced a different sort of calamity equally near at hand. Mr. Mitchell was followed shortly by Albert H. Wiggin, head of the Chase National Bank, William Potter, head of the Guaranty Trust Company; and Seward Prosser, head of the Bankers Trust Company. They had come to confer with Thomas W. Lamont of the Morgan firm. In the space of a few minutes these five men, with George F. Baker, Jr., of the First National Bank, agreed in behalf of their respective institutions to put up forty millions apiece to shore up the stock market. The object of the two-hundred-and-forty-million-dollar pool thus formed, as explained subsequently by Mr. Lamont, was not to hold prices at any given level, but simply to make such purchases as were necessary to keep trading on an orderly basis. Their first action, they decided, would be to try to steady the prices of the leading securities which served as bellwethers for the list as a whole. It was a dangerous plan, for with hysteria spreading there was no telling what sort of debacle might be impending. But this was no time for any action but the boldest.

The bankers separated. Mr. Lamont faced a gathering of reporters in the Morgan offices. His face was grave, but his words were soothing. His first sentence alone was one of the most remarkable understatements of all time. “There has been a little distress selling on the Stock Exchange,” said he, “and we have held a meeting of the heads of several financial institutions to discuss the situation. We have found that there are no houses in difficulty and reports from brokers indicate that margins are being maintained satisfactorily.” He went on to explain that what had happened was due to a “technical condition of the market” rather than to any fundamental cause.