Banks globally, especially European ones, are seen as increasingly vulnerable to European debt problems. The total exposure of the global banking system to Greece, Ireland, Portugal, Spain and Italy is more than $2 trillion. French and German banks have huge exposures.
If there are defaults, these banks will need capital, most likely from their embattled sovereigns. European banks shares have been hammered, with French bank
Société Générale's shares falling nearly 50% in a short period. Deutsche Bank's head fears many smaller banks may not survive sovereign defaults.
In the US, concerns about Bank of America have emerged, with analysts suggesting it requires significant infusions of capital. Its shares have fallen by about 40% in the past month. Its decision to issue $5 billion in preference shares to Warren Buffett's Berkshire Hathaway, now confirmed as the markets' lender of last resort, at distressed prices was a statement of weakness.