June acreage survey and quarterly stocks — historically one of the most volatile report days.
After 3,207 past report events, Corn moved a median +0.2% over 5 sessions (54% higher; middle half -1.3% to +1.7%), and +0.5% over 20.
After 2,389 past report events, Soybeans moved a median 0.0% over 5 sessions (50% higher; middle half -1.6% to +1.9%), and +0.1% over 20.
After 2,447 past report events, Wheat (SRW) moved a median +0.0% over 5 sessions (51% higher; middle half -1.5% to +1.8%), and +0.2% over 20.
After 1,283 past report events, Soybean Meal moved a median -0.1% over 5 sessions (47% higher; middle half -2.0% to +1.7%), and -0.2% over 20.
Moves of each commodity's benchmark from the last close before the event. Historical reads pool past events of the same kind; they describe what happened, not what will. Not investment advice.
The June 28, 2019 USDA Acreage report showed corn plantings near 91.7M acres, far above trade expectations despite the wet planting delays, and quarterly stocks came in higher than expected; that bearish supply surprise drove the sharp same-day selloff.
The USDA Acreage and Grain Stocks reports on 2019-06-28 (a Friday) were released just before the Monday 2019-07-01 move and could have shifted supply expectations for wheat; the summary gives no figures, so the direction and size of the surprise are unconfirmed and the link is plausible but not certain, especially since corn-led spillover or a delayed reaction could also be involved.