“The BGOV Barometer shows that, over the five decades since John F. Kennedy was inaugurated, $1,000 invested in a hypothetical fund that tracks the Standard & Poor’s 500 Index (SPX) only when Democrats are in the White House would have been worth $10,920 at the close of trading yesterday.
That’s more than nine times the dollar return an investor would have realized from following a similar strategy during Republican administrations. A $1,000 stake invested in a fund that followed the S&P 500 under Republican presidents, starting with Richard Nixon, would have grown to $2,087 on the day George W. Bush left office.”
From thinkprogress.