Higher incomes due to a college education were a key reason middle income households gained income share relative to those in the lower part of the distribution between 1973 and 2005. This was due in part to technology changes. However, education had less impact thereafter. Further, education did not explain why the top 1% gained disproportionately starting around 1980. Causes included executive pay trends and the financialization of the economy. For example, CEO pay expanded from around 30 times the typical worker pay in 1980 to nearly 350 times by 2007. From 1978 to 2018, CEO compensation grew 940% adjusted for inflation, versus 12% for the typical worker. A 2012 study reported that the main occupational shift for the top 1% was towards finance, while in 2009 "the richest 25 hedge-fund investors earned more than $25 billion, roughly six times as much as all the chief executives of companies in the S&P 500 stock index combined."