The S&P GSCI, a benchmark for investment performance in the commodity markets, registered its biggest one-month gain in May since Iraq invaded Kuwait in September 1990. The index was up 19.67% in May compared with a gain of 22.94% in September 1990.

Solid commodity gains in May were attributed to most commodities accelerating the recovery process from the sharp declines experienced during the second half of 2008 and first quarter of 2009 according to Michael McGlone, director of commodity indexing at Standard & Poor's.

Year-to-date the S&P GSCI has registered a total return of 5.95%, led by strength in the energy and agriculture sectors. Price increases in unleaded gas and crude oil helped the S&P GSCI Energy Index rise 25.44% on the month for a year-to-date gain of 4.38%.

The S&P GSCI Agriculture Index was the second best sector performer in May increasing 12.37% for a year-to-date gain of 8.18%.

Metals also performed well in May with an 11.41% increase in the S&P GSCI Precious Metals Index. Year-to-date metals are up 12.71%.

The S&P GSCI Industrial Metals Index increased 5.82% on the month while the S&P GSCI Industrial Metals Index has been the strongest year-to-date sector performer with a gain of 22.23% led by the 55.72% increase in the S&P GSCI Copper Index.