It's an open question which party's policies are better for the economy, but the stock market does much better under Democratic presidents.
On Tuesday, the Dow Jones Industrials Average topped 13,000 for the first time since March 2008. That set off a predictable round of crowing from liberals and sniping from conservatives. Those on the right griped that President Obama, having villainized the financial industry, would now attempt to make political capital from the market's improvement.
That complaint is silly. Whether Obama has "villainized" the sector is both subjective and, in this case, mostly irrelevant: only three members of the Dow's 30-stock index are financials: Bank of America, JPMorgan, and American Express, and the broader market, which it tracks, also consists of more non-bank stocks than bank stocks (obviously).
Who gets credit for what is an important question. As Ezra Klein has pointed out, we're likely to see an improving economy between now and 2016, so whoever is elected in November will preside over a relative boom, and he and his party's policies will receive credit for it, which could have long-lasting effects (see the Democratic Party's dominance in the post-FDR years). But the stock market doesn't really tell us much, since it measures the extent to which equities are gaining in value, not how much the economy is improving.