For six consecutive years, funds that passively track broad market indices climbed higher, but passively managed funds only brought in $393.3 billion for the first 11 months of the year, or a 37% decline year-over-year for the same period.

“An aging bull market coupled with periods of market volatility, political uncertainty and rising interest rates has led to investors becoming more cautious,” a spokeswoman for Vanguard said.

Meanwhile, active managers long contended that volatility would help them gain an upper hand as they would be better placed to adapt to sudden market changes. However, investors continued to yank money from the funds. For the first 11 months of 2018, active funds experienced $156.2 billion in net outflows, marking the third year of withdrawals for the period of the last four.

The disparity between active and passive continues as December volatility shocked investment confidence. According to the Investment Company Institute, mutual funds suffered redemptions of $56.2 billion for the week ended December 19, its biggest outflow since the week ended October 15, 2008. In comparison, investors added $25.2 billion into ETFs over the same week, especially among corporate insiders, Bloomberg reports.

ICI Chief Economist Sean Collins said in a statement that it reinforced the view that “some investors view periods of volatility as a buying opportunity.”