Shocks and crashes

"Three shocks, distinguished by whether their effects are permanent or transitory, are identified to characterize the post-war dynamics of aggregate consumer spending, labor earnings, and household wealth. The first shock accounts for virtually all of the variation in consumption and has effects akin to a permanent total factor productivity shock in canonical frictionless macroeconomic models. The second shock underlies the bulk of fluctuations in labor income, accounting for 76% of its variation. This shock permanently reallocates rewards between shareholders and workers but leaves consumption unaffected. Over the last 25 years, the cumulative effect of this shock has persistently boosted stock market wealth and persistently lowered labor earnings. The third shock is a persistent but transitory innovation that accounts for the vast majority of quarterly fluctuations in asset values but has a negligible impact on consumption and labor earnings at all horizons. We show that the 2000-02 asset market crash was the result of a negative transitory wealth shock, which predominantly affected stock market wealth. By contrast, the 2007-09 crash was accompanied by a string of large negative realizations in both the transitory shock and the permanent productivity shock, with the latter having especially important implications for housing wealth"--National Bureau of Economic Research web site.