When the New York markets open on Monday, all eyes will be on Wall Street’s banks. As the US Federal Reserve, in a bid to ease the liquidity crisis, holds a novel type of money market auction to inject some $20bn of funds into financial institutions, investors and policymakers will be watching closely to see how many large banks bid for how much cash – and what that, in turn, indicates about their state of health.

Yet while investors are scrutinising some of the industry’s best-known names, a spectre will be silently haunting events: the state of the little-known, so-called “shadow” banking system.