Many consumer advocates consider payday loans—short-term, uncollateralized loans with high interest rates—to be predatory. The demand for short-term funding has spurred the quest for a substitute, an effort encouraged and supported by regulators like the Federal Deposit Insurance...

In February of 2008, the $330 billion auction-rate security market began to fall apart. Brokerage houses that managed the periodic auctions refused to support their issues, so that auctions failed and liquidity disappeared. Investors had a wake-up call: an asset they had thought was a...