Boeing Co. shares are in free fall after this weekend’s deadly air crash, and trading in exchange-traded funds exposed to the manufacturing giant has gone through the roof.

The SPDR Dow Jones Industrial Average ETF Trust, traded as DIA, saw more than four times its average pre-session volume as its Boeing exposure spooked investors. Over 265,000 shares of the US$21.1 billion fund traded before 9:30 a.m. in New York, the most since Jan. 30. The fund tracks the gauge of U.S. blue-chip stocks, of which Boeing is the heaviest weighting with 11 per cent.

About 83,000 shares of the US$10.4 billion Industrial Select Sector SPDR Fund, ticker XLI, exchanged hands before stock markets opened in New York Monday. That’s more than nine times the average pre-session volume over the past year, and the most since Dec. 24.

Boeing sank as much as 13 per cent Monday, and is set for the biggest slide since January 2016 as the company deals with the fallout of a crash Sunday involving one of its 737 Max jetliners. The disaster -- the second involving this model -- has prompted some airlines to ground the best-selling plane. The model generates almost one-third of the manufacturer’s operating profit.