Why markets can never be made truly safe

Collateral is usually a boring affair. Valuing assets and extending credit against them is the preoccupation of the mortgage banker and the repo trader, who arranges trillions of dollars a day in repurchase agreements for very short-term government bonds. This activity is called financial plumbing for a reason: it is crucial but unsexy. And like ordinary plumbing, you hear about it only when something has gone wrong.