That may be, but you would have a difficult time showing cause and effect to such a claim. A Republican controlled Congress, combined with a Democratic President could spark the stock markets. Here is is some information on the historical performance of the Markets under various party rule scenarios.
http://www.bloomberg.com/news/2010-0...n-dorfman.html
A war may be in store for Republican leadership should they prevail with a majority. In years past, they have been able to maintain a very tight grip on their membership. The Tea Party movement is an unknown. In many cases Tea Party candidates were not supported and contested quite vigorously by Republican the Party.
Just today Karl Rove came out with a statement that Palin is not fit to be President. As true as that may be, it does demonstrate the rift between traditional party leadership and the Tea Party populist movement. In a nut shell, the Republicans may suffer from the same disarray that has plagued the Dems for years. A very strong and vibrant fringe wing that cannot always be counted on to step in line. It should be interesting.