Deutsche Bank private wealth management issued a report on "Bearing in on an Olympic Hangover" and concluded the following:
"Some may call it coincidence but historically commodity prices have rallied in the run up to the Olympics. Since 1980, when commodities have rallied in the year preceding the start of the Olympics (1980, 1988, 1996, 2000), returns were negative in the following year. The only exception was in 2004 as the commodity strength continued after the Olympics. In 1992, commodities strengthened after the games but lacked a rally in the year before the Olympics."
Anyway... the conclusion is attached... and you may want to read my previous write up on the Commodities.