This article at the BBC news web site points out that stock markets do better under Democratic administrations than Republican ones. While it seems like the evidence for this is genuine, the following observation (taken from the article) probably pushes it too far:
"Indeed, a recent study published in the New York Times showed that $10,000 (£6,263) invested in the S&P 500 in 1929 would have grown to $11,733 if invested under Republican presidents, but to $300,671 under Democratic presidents."
It sounds like a fun fact to point out to a US voter with a defined-contribution pension scheme. But, I note that it was Republican president Herbert Hoover who presided over the 1929-33 Depression, so perhaps the Democrats had a bit of a headstart in this race. (Meanwhile, share prices right now are still doing badly. But I guess Obama hasn't been sworn in just yet.)