The three biggest banks in the nation—Citigroup, Bank of America, and J.P. Morgan Chase—have agreed on the structure of a $75 billion fund intended to prop up troubled short-term commercial debt, according to several reports.

With an agreement in place, the three can now start signing up other banks over the next 10 days, reports David Wighton in the Financial Times.

Eric Dash in the New York Times says the question now is whether the superfund will actually help.

Not much, according to analysts and investors cited by the Times.

"The backup fund will not save troubled structured investment vehicles, or S.I.V.'s, that hold billions of dollars in packaged loans, though it could delay their demise. It may help calm the turbulent credit markets by preventing a sharp sell-off of securities, though analysts say the fund will probably not be able to offset the deteriorating prices of the securities," the Times says.

Indeed, the purpose of the superfund, or as the banks call it, the Master Liquidity Enhancement Conduit, is simply to delay the day of reckoning.

But even that may not be possible, as the credit markets continue to deteriorate.

And because S.I.V.'s use so much leverage, if the bulk of S.I.V. assets are "fetching between 97 cents and 98 cents on the dollar," as the Times says, then many S.I.V.'s may in fact be on the brink of forced liquidations, says the blog Calculated Risk.

If the N.A.V. for an S.I.V. falls below 50 percent, the vehicle may have to be liquidated, according to Fitch Ratings.

Calculated Risk explains, "If an S.I.V. had $1 billion in capital, and an additional $14 billion in leverage (mostly from selling commercial paper and medium-term notes), the S.I.V. would hold $15 billion in assets. If the typical asset was ‘fetching between 97 cents and 98 cents on the dollar,' that would be a loss of $300 million to $450 million, or a loss of 30 to 45 percent of capital (from the $1 billion) giving an N.A.V. of 55 percent (97 cents on the dollar) to 70 percent (98 cents on the dollar)."

Terms of the fund may be ready in the next two weeks, after ratings companies evaluate the superfund and the banks obtain tax and legal opinions, Bloomberg News reports, citing a person familiar with the talks.

Still, it is clear that the plan, despite a blessing from the Treasury Department, must overcome growing skepticism about its effectiveness.

"The whole thing is flawed," Josh Rosner, a managing director of Graham Fisher & Co. in New York, told Bloomberg. "As opposed to recognizing losses, we're trying to roll those losses into the future, regardless of the sanity or safety and soundness of doing that."