7 October 2008: Fed offers to buy commercial paper directly

With the short-term lending market that companies use to pay wages and suppliers seizing up, the Federal Reserve announced the Commercial Paper Funding Facility, offering to buy that debt directly from issuers. It was a startling step for a central bank and showed how deep the panic had gone. Stocks still fell sharply that day, as investors wondered what else was broken.

The lesson: The plumbing of finance is invisible until it clogs, and then it is all anyone sees.