Many of the wealthy are as concerned to protect their paper wealth as to borrow against it. For the southern rubbish collector, Warburg provided a combination of options called a zero-cost collar that is especially popular among the one-stock wealthy.

Merrill's move into social work is an example of how investment banks are serving one of their fastest-growing client groups, the one-stock wealthy — typically internet pioneers or entrepreneurs who have made billions by taking their companies public or selling them for shares.