The public disclosure of so-called “living wills” of large, systemically-important banks that was made this week doesn’t do much to explain how such banks would actually be resolved if they failed.

Earlier this week U.S. banking regulators revealed the public portion of the living wills that the biggest banks (those with more than US$250 billion in assets) are being required to create to show how they could be wound down without disrupting financial markets. Yet Fitch Ratings says that those disclosures, “offer few, if any, new details on the process by which banks and regulators would smoothly dispose of assets in a default scenario.”

The rating agency says that much of the content in the public living will documents was identical to previous public disclosure, and offered only a general framework for the hypothetical treatment of bank assets and liabilities upon insolvency.

Moreover, it believes that these plans still depend heavily on “implicit assumptions related to regulatory cooperation and market liquidity in any future crisis that might involve the failure of one or more major institutions”.

One implicit assumption, it points out, is that regulators would work collaboratively across borders to ensure that an orderly wind-down of an institution could take place. Yet, Fitch says, “given the territorial nature of bank regulation and the difficulties faced by various regulatory agencies in their home markets, we see this as a problematic assumption that may not be applicable in any future global financial crisis involving large bank failures until and unless there is broad harmonization of bank resolution regimes.”

“Another key issue raised by the living will documents is the potential for any future crisis to necessarily involve a high degree of systemic risk aversion that would make the timely disposal of assets and the liquidation of any single bank’s operations difficult,” Fitch adds.

It says that, while it’s conceivable that a single global institution could fail in isolation, “this is by no means the most likely distress scenario in light of the potential for multiple banks to confront simultaneously similar macro and liquidity pressures at the time of default, forcing banks and regulators to dispose of assets in illiquid markets.”