The more likely explanation:
Go there for information on obtaining the files and additional commentary.
If you just assume away the weekends, as I did above, it's more likely that the Dow leads the Obama contract than vice versa*.
Falling Dow is a leading indicator of a sour economy, the sour economy favors the party out of (executive) power.
*Uses Granger Causality test, two lags, for those who want the econometrics. EViews file available.