U.S. lenders appear to present a bigger risk to the financial system than last year. Citigroup (NYSE:C), BofA (NYSE:BAC) and Wells Fargo (NYSE:WFC) all face higher capital surcharges after they rose in the Financial Stability Board’s latest ranking of the most systemically important banks in the world, while HSBC, Barclays (NYSE:BCS) and Morgan Stanley (NYSE:MS) saw their buffer levels fall.