The study looked at how different economic shocks affected real US stock prices from 1947 to 2011. They found that shocks like changes in money supply and spending had a big impact on stock prices, especially during the "Great Recession". The drop in stock prices during that time was mainly because of a slowdown in US productivity and investors moving their money out of stocks. Overall, the study shows that various economic shocks from different sectors of the US economy caused the decline in stock prices during the "Great Recession".