The new Basel III banking rules will leave the biggest U.S. banks short of between $100 billion and $150 billion in equity capital, with 90 per cent of the shortfall concentrated in the top six banks, Reuters said, based on a report in the Financial Times.

The newspaper said the study by the investment banking arm of Barclays plc assumes the banks will need to hold top-quality capital equal to 8 percent of their total assets – a one-point cushion against falling below the effective global minimum of 7 percent set in September by the Basel Committee on Banking Supervision.

The regulations mean banks may need to increase their capital by retaining earnings or issuing equity, or they can cut their risk-weighted assets by selling off assets and cutting back riskier business.

“These shortfalls are entirely manageable. … The more difficult question is what effect the new rules will have on the cost and availability of credit and bank profitability,” Tom McGuire, head of the Capital Advisory Group at Barclay’s Capital, told the Financial Times.

McGuire estimates that U.S. banks can cut their equity needs by $10 billion with each $125 billion reduction in risk-weighted assets, the Financial Times article said.