The election of President Donald Trump is eclipsed only by the 9/11 terrorist attack and the battle over the fiscal cliff in 2011 in terms of generating doubt about future economic policy, CNBC reported, citing the Economic Policy Uncertainty Index.

Increases “in policy uncertainty foreshadow declines in investment, output, and employment in the United States,” the three professors from Stanford, the University of Chicago, and Northwestern who created the index wrote in a 2016 paper, CNBC reported.

They do not say recession necessarily follows, only that there is a measurable economic effect from uncertainty, and they urge lawmakers to keep that in mind.

From the standpoint of creating economic uncertainty, the election of Trump has been more tumultuous than the 1987 stock market crash and the 2008 financial crisis.

Judged by the index, Trump’s election stands as the third-biggest source of uncertainty in the index’s 30-plus-year history. It is eclipsed