King Rex

A stock baron goes all in on Missouri politics.

By LEE FANG

Rex Sinquefield amassed a fortune by doing nothing. Well, not exactly: In the 1970s, he pioneered the first index funds, investment vehicles that strictly track a broad portfolio of financial assets, such as the S&P 500, leaving no room for individual error or hunches. He did so by capitalizing on a theory, honed by his intellectual mentors at the University of Chicago, that such “passive” investments in the overall market could outperform even the best stock pickers in the country. “Private investment managers can’t beat markets,” he likes to say.

But he prefers his politics a lot less passive: The 69-year-old retired multimillionaire is now betting that he can pick political winners and losers back in his native Missouri.