In the wake of the credit crisis, it might have been assumed that investors would usher in a new era of discipline and rigorous analysis. Indeed, the sheer scale of their losses in instruments ranging from leveraged loans to asset-backed commercial paper and complex securitisations should have made investors more defensive.

But in the past few months, as signs that the credit rally is nearing an end, investors' clamour for new sources of yield has intensified. Some practitioners say discipline has begun to slip, evoking memories of the carnage that ensued the last time bankers could sell whatever they wanted.