Tax-policy change and trade data triggered the largest Dow points loss to date

Evidence

On Wednesday October 14, disappointing data on the trade deficit and moves by the Ways and Means Committee of the House of Representatives to remove tax advantages that had contributed to the mergers and acquisitions boom led to what was then the largest number of points ever lost by the Dow Jones average in a single day. — Donald MacKenzie, An Engine, Not a Camera, 817