One of the factors driving stock prices are earnings. ISM data are improving in the US, so that is another factor that could lend support to stock prices, despite news such as Moody's downgrade of Portugal debt to junk yesterday. But remember organisations such as Moody's and S&P ratings are the same ones that gave AAA rating to the subprime CDOs.(Collaterised Debt Organisations) Still credible? When asked in the US Congressional enquiry on the GFC and the role the credit ratings agency assesses ratings, they said "We are just expressing an opinion..." And as 2008 proved, this opinion is not worth anything...