By Frank Holmes, CEO and Chief Investment OfficerNEW YORK ( U.S. Global Investors) -- After the first few months of President Barack Obama's term in office, I wrote about the carnival roller coaster the market was riding. Looking at the blue line in the chart below, that post may have foreshadowed his tenure! The average of four-year presidential cycles from 1953 through 2008 shows that the S&P 500 index generally remains flat for almost the first two years, before heading higher in the second half. Despite the S&P's wild ride, the market is significantly higher than when Obama took the oath. Does this ensure a victory for the 2012 election? To paraphrase common fund disclosure, past performance is not indicative of future presidential performance. Rather, victory for the president depends on what the market does in the next few critical months. If the S&P remains strong, then the answer might be yes, says Adam Hamilton from Zeal Intelligence. He points to research done by InvesTech, which looked at market results during the two months leading up to the presidential election since 1900. If stocks rise in September and October, the incumbent party usually wins the presidency; if equities drop, the incumbent typically loses. "Out of the last 28 presidential elections, this simple indicator has proven correct 25 times. This is an astounding 89 percent success rate," he says. Piper Jaffray found very similar results. The firm reviewed the S&P 500 performance for the three months prior to an election year since 1928. According to its study, the incumbent party won 11 out of 14 times when the S&P rose, and lost six out of seven presidential elections when the S&P declined over the three months. So why does this happen? It's the market's effect on Americans' psyche. Hamilton says, "When the stock markets are strong so everyone feels better about the future, incumbents are more likely to win." He explains what many of us feel: When stock prices are rising, people are more optimistic and spend more; when markets take a turn for the worse, people become concerned and spend less. "Not surprisingly, these behavioral changes spawned by our rising and falling portfolios also carry over into the voting booths," he says.