Grains-Corn retreats on profit-taking after prior-day rally on USDA data

Chicago Board of Trade December corn CZ26 ended down 8-3/4 cents at $4.72 a bushel, while November soybeans SX26 settled a penny lower at $11.82-1/4 a bushel. CBOT September wheat WU26 was unchanged at $6.52-3/4 a bushel.

Strong export demand underpinned the soybean market after a strong week of sales last week and continued new-crop buying by top importer China.

Large global supplies of corn and soy kept a lid on both markets following crop production updates from major exporters Brazil and Argentina.

Traders are turning their attention to a major field tour next week that will give another indication of yield prospects for U.S. corn and soybeans, with forecasts for rain this week tempering some yield concerns.

Wheat markets continued to monitor hostilities between Russia and Ukraine, where attacks on grain infrastructure have accelerated and reduced shipments.

"If there's no solution within the next two weeks, I think the market will have to factor this in much more than it currently is," Maxence Devillers, a grain analyst with Argus Media, said.

CHICAGO, Aug 13 (Reuters) - U.S. corn futures fell on Thursday in a profit-taking retreat following sharp gains a day earlier, pressured by large South American crops and forecasts for beneficial Midwest rains over the next week.

Soybeans ended mixed as support from strong export demand was offset by favourable U.S. crop weather and hefty South American supplies. Wheat futures were narrowly mixed after shedding early-session gains that were triggered by the threat of prolonged disruptions to Black Sea exports.

Grain markets adjusted following volatile price moves a day earlier after the U.S. Department of Agriculture increased its 2026 U.S. corn and soybean plantings estimates while lowering its outlook for average yields in a monthly report.