Fortunately, these dangers are being recognised, thus, for example, imposing a levy on uninsured liabilities of banks, or on a surrogate for the value-added of the banking system, seems more likely to have an acceptable ratio of deadweight cost to revenue, than other forms such as a tax on interest rates, or than a general tax on bank transactions as has been proposed by some, but which would in my view not generate as much revenue as is often supposed, and would not be effective in discouraging the forms of financial excess that caused the crisis.
It may be that well-targeted corrective Pigouvian taxes can do even better, for example if they are targeted at excessive reliance by banks and other financial firms on short-term borrowing.