Asian markets rallied overnight as Moody's mulled raising the ratings of some Asian countries, while investors pinned their hopes on an EU summit to solve the debt crisis.
UK Prime Minister David Cameron has threatened to veto plans for an overhaul to the EU treaty on grounds it could damage British interests.
The Bank of England is readying emergency funds designed to protect the UK economy from "unexpected shocks".
Ratings agency Standard and Poor's (S&P) said France and Germany are among 15 nations that have been put on "credit watch" due to fears over the impact of the debt crisis.
The S&P 500 has risen 1.7%, with European equity markets also holding onto gains after German Chancellor Angela Merkel and French President Nicolas Sarkozy reached accord on the debt crisis.
As the eurozone crisis reaches a crescendo, the Bank of England has revealed just how much exposure UK banks have to the region's most troubled economies.
European stock markets opened higher this morning ahead of a crucial eurozone meeting on Friday which could decide the future of the single currency.
Yields on Swedish government bonds have dropped to their lowest ever levels relative to Germany today as investors flee traditional safe havens amid the eurozone panic.
German Chancellor Angela Merkel helped lift markets further today after revealing moves towards "fiscal union" in Europe were afoot.