"In Capital Adequacy Beyond Basel: Banking, Securities, and Insurance, Hal Scott looks beyond the second generation of the Basel rules for banks to show that banking rules do not fit easily with the activities of securities or insurance firms, which engage in different activities and whose failure poses much less risk to the financial system. The inability of bank-based rules to deal adequately with different activity risks is reflected in the difficulty in applying Basel rules to bank holding companies that engage in nonbanking activity through non-bank subsidiaries." The book also addresses the Basel approach to operational risk, suggesting that operational risk is extremely difficult to identify and quantify. It questions why capital should be required for low-loss, high-frequency events, which are dealt with through reserves or provisions, or high-loss, low-frequency events that are dealt with by insurance. The main risk for which banks, and other firms, hold the most capital is business risk, and Basel requires no capital for this.