King made his remarks Monday afternoon at the Economist magazine’s Buttonwood conference in Manhattan.

In his speech, King weighs the costs and benefits of various approaches to limiting bank risk-taking, ranging from taxes to higher capital requirements and bigger liquidity pools. He indicates none of these approaches will be sufficient on its own, but stresses that policymakers must use all available tools to make sure that bank shareholders — and not taxpayers — grab the check when bankers run amok.

The rulemakers must approach this puzzle thoughtfully but act promptly, King said. Otherwise they risk letting errors by massive, tightly interconnected financial institutions bring the globe once again to the edge of the abyss.

“The current system is not sustainable,” King said.

On his way to that discussion, he notes one major problem that has both driven the explosion of risk-taking and gotten worse in the aftermath of the crisis: the massive expansion of giant banks wallowing in what he calls “absurd” leverage. For instance:

Bank of America today accounts for the same proportion of the US banking system as all of the top 10 banks put together in 1960.

And what do we have to show for it? You might well ask. The economy is now beset by the costs of bailing out the banks and uncertainty over how badly they have botched their mindbending mortgage shuffling game. And if we don’t pass new rules soon, BofA and its brain-dead brethren may bring the whole house of cards tumbling down again.

Not everyone is complaining, mind you. For instance, BofA chief Brian Moynihan has made $20 million over the last three years. A look at the lavish pay packages of his predecessor, Ken Lewis – the guy who brought BofA shareholders the Countrywide nightmare — suggests Moynihan may soon be bringing in that much annually.

One wag at the conference suggests tallying up the salaries of those 10 bank CEOs in 1960 and adjusting them for inflation. It is highly unlikely, he suggests, that those would sum to $20 million or whatever Moynihan will be pulling down whenever BofA finally pulls off its oft-promised turnaround.

Of course, given BofA’s performance in this crisis — careening from bailout to bailout while foreclosing on mortgages it doesn’t even own – a sustained turnaround is far from a foregone conclusion. It would be nice to think that some sort of success on that count would be a precondition to making unimaginable sums of money, but for the typical CEO now it just isn’t so.