While it is well known that a Tobin tax would have little effect on markets unless all major financial centers adopted it, what is true of markets is not necessarily true of financial institutions. If, say, French President Sarkozy wanted to stop too-big-to-fail French financial institutions from transacting in ways that weaken them, a Tobin tax on their transactions, wherever in the world they occurred, could work; the tax would affect the institutions, even if it could not shape world-wide markets.