One of the reasons that the financial crisis got as bad as it did was because of the amount of leverage employed by Wall Street as the economy went into a recession. The market decline was exacerbated if not caused by the mass deleveraging of the financial sector over the course of several of months. For instance, Goldman Sachs went from $1.1 T in assets in 2007 to $880 B at the end of 2008. Since it raised capital at the same time, the leverage ratio fell from a high of 26x to a low of 11.8x in 2010.
As securities markets have recovered investment bank balance sheets are growing again, although, using $GS as a proxy, leverage is still much better than it was in 2007. If recession is on the visible horizon, perhaps this will help to soften any market decline.