Et tu, Dominique? Banks knew they had enemies, but they were plainly surprised by the International Monetary Fund's sweeping proposals to the Group of 20 industrialised nations for the financial sector to make a “fair and substantial” contribution. Given the popular mood towards banks these days, what is fair hardly matters. Defining substantial, however, certainly does.

Of the proposals, a flat-rate levy on liabilities was expected. But a second, gloriously named FAT (financial activities tax), on profits and remuneration, was not. The proposal to require all financial institutions, including insurers, to pay a levy, rather than a select group deemed systemically important, is also an unpleasant surprise for investors.

The IMF report will now frame the debate, and not merely because its wonks came up with a headline-friendly acronym. Banks might yet succeed in portraying the Securities and Exchange Commission as politically motivated, but it will be harder to perform the same trick on the IMF, hitherto a rigid enforcer of markets-based orthodoxy.