John Allen Paulos, in his book, A Mathematician Plays the Stock Market, reveals the highest correlation ever found to the S&P 500: It was the amount of butter produced in the country of Bangladesh. Apparently, between 1983 and 1993, when butter production was up 1 percent, the S&P 500 was up 2 percent the next year. Conversely, if butter production was down 10 percent, you could predict the S&P 500 would be down 20 percent.
