Are mysterious commodities traders like Glencore and Noble too big to fail?

When Glencore's share price plummeted on Monday and billions of dollars of its chief Ivan Glasenberg's wealth vanished into thin air, a company spokesman moved to dismiss an outlandish comparison to Lehman Brothers.

There was no global catastrophe and Glencore had neither the business model nor the indebtedness of that collapsed US investment bank, we were assured.