$CTVA shows -81.78% before the bell. Corteva is a roughly $51.9B company, and this morning's headline contains no loss, no miss and no guidance cut. It says "Begins New Chapter as Focused, Innovation-Led, Global Crop Protection Leader."
In corporate English, "focused" usually describes what remains after something is gone. So the useful question for anyone staring at that quote is what left and where it went. How a crop company lost four-fifths of itself overnight is the wrong question.
The price quote can't answer that. The release can. Check what holders of the old shares now own before you read -81.78% as damage.
Corteva put out a second release this morning: expiration and final results of private exchange offers and consent solicitations for EIDP's 2.300% notes due 2030, 5.125% notes due 2032 and 4.800% notes due 2033. Bondholders being offered new paper for old is plumbing. It points the same way as "focused": the structure underneath the ticker is being rearranged, and the structure comes before the chart.