By Iona Bain

Global markets have staged a strong comeback in 2011, with America making its biggest gain in one month since 1997.

According to S&P, 45 out of 46 world markets grew in January and earned back 60% of their losses after a gloomy 2011. Developed markets were up 6.11% and only Portugal was down by 3.42% after it was forced to pay higher rates to sell its debt.

Experts have attributed the turnaround to a "new round of optimism" about the management of European debt and the stability of America's economy.

Emerging markets posted a particularly robust performance - up 11.56% - with BRIC countries significantly outperforming their peers. Brazil was up 14.81%, Russia 14.23% and India 20.42%, and even China defied expectations for a slowdown with a 10.84% gain in January.

Howard Silverplatt, senior index analyst at S&P indices, has pointed out the Super Bowl Theory could already be taking effect - any year that a champion of the National Football Conference wins the epic game, the American stock market goes up.

This is good news for superstitious investors, as the New York Giants won against the New England Patriots in last night's game.

But he also pointed to fourth-quarter earnings among American companies, which were higher than previously expected.

Stephen Barber from Seltrade, the execution-only stockbroker, says: "There are some good numbers emerging from US companies at the moment, which analysts hope will lead to growing confidence in the US economy.

"Confidence is much needed, not simply that of consumers but more fundamentally confidence in the boardrooms. American companies continue to sit on billions of dollars of reserves whose deployment will have a very positive economic effect."