The Obama administration is expected today to propose a reorganisation of the way we regulate financial markets. I am not an advocate of too much regulation. Having gone too far in deregulating – which contributed to the current crisis – we must resist the temptation to go too far in the opposite direction. While markets are imperfect, regulators are even more so. Not only are they human, they are also bureaucratic and subject to political influences, therefore regulations should be kept to a minimum.

Three principles should guide reform. First, since markets are bubble-prone, regulators must accept responsibility for preventing bubbles from growing too big. Alan Greenspan, the former chairman of the Federal Reserve, and others have expressly refused that responsibility. If markets cannot recognise bubbles, they argued, neither can regulators. They were right and yet the authorities must accept the assignment, even knowing that they are bound to be wrong. They will, however, have the benefit of feedback from the markets so they can and must continually re-calibrate to correct their mistakes.

Second, to control asset bubbles it is not enough to control the money supply; we must also control the availability of credit. This cannot be done with monetary tools alone – we must also use credit controls such as margin requirements and minimum capital requirements. Currently these tend to be fixed irrespective of the market's mood. Part of the authorities' job is to counteract these moods. Margin and minimum capital requirements should be adjusted to suit market conditions. Regulators should vary the loan-to-value ratio on commercial and residential mortgages for risk-weighting purposes to forestall real estate bubbles.