Ratings agency Fitch has said the updated fiscal and economic projections from the UK's Office for Budget Responsibility mark a "significant deterioration" in prospects.
Investors should ready themselves for a stronger gold price correction, said investment veteran Jim Rogers.
The European equity fund market has nearly halved in size since 2007, slimming down to €314bn in assets under management at the end of September 2011, according to a Fitch report.
Fitch has become the third ratings agency to downgrade the outlook for the US, from stable to negative, following a congressional committee's failure to finalise deficit cuts.
Credit rating agency Fitch has downgraded Portugal's credit rating from BB+ to BBB- due to its fiscal imbalances and high indebtedness, and the worsening outlook for Europe.
S&P and Fitch have downgraded some of Spain's largest financial institutions including bank Santander, citing a deteriorating outlook for the Spanish economy.
Italian and Spanish government debt have both been downgraded by the Fitch credit rating agency.
Fitch Ratings has joined up with Lipper to launch a fund rating service which combines Fitch's qualitative fund analysis with Lipper's rankings and performance data.
Fitch Ratings, the US fund rating service, is to launch a fund rating service covering UK funds as part of a new offering aimed at professional investors.
Fitch has downgraded Greece to CCC status, one notch above default, due to growing concerns private investors do not want to participate in any bailout of the country.