Like most people, you probably assume that the level of lending done by banks at any moment is largely driven by how much demand there is from borrowers. But in the world of modern finance, that’s only part of the story. For just as important is the level of demand from investors — pension funds, hedge funds, mutual funds, sovereign wealth funds and insurance companies — to buy the loans that banks make. Indeed, there are times when there’s so much demand for loans from investors and the profit from selling them is so lucrative that bankers are only too happy to go out and make bigger and riskier loans than they would if they were keeping them on their own books.