CHICAGO, Jan 11 (Reuters) - Chicago Board of Trade soybean futures ended flat on Thursday and remained near their lowest level since December 2021 amid lackluster demand for U.S. exports and an improved South American supply outlook.

Corn futures eased and were close to their lowest level since December 2020. Wheat futures also slumped.

Traders adjusted positions while awaiting the release of quarterly U.S. Department of Agriculture (USDA) grain stocks data and a monthly agricultural supply/demand report on Friday. The data can set the tone for grain and oilseed markets through the first part of the year.

"We've been down in both corn and beans quite a bit coming into this report," said Ted Seifried, chief market strategist for the Zaner Group. "The market has kind of paused."

Most-active CBOT soybean futures ended unchanged at $12.36-1/2 a bushel, near the session low of $12.34-1/4. On Tuesday, the market reached $12.34, the lowest in more than two years.

Corn finished down 1-3/4 cents at $4.57-3/4 per bushel after falling to a three-year low of $4.51-3/4 on Tuesday. Wheat settled 7 cents lower at $6.03-3/4 per bushel.

Analysts expect the USDA on Friday will report U.S.

corn stocks

stood at 12.05 billion bushels as of Dec. 1, which would be up 11.4% from a year earlier and the largest stock level for that date since 2017. Stocks of wheat are also expected to be up from a year earlier, while soybean stocks are seen lower.

Traders will also closely review the USDA's estimates for South American corn and soy production, after hot, dry weather hurt crops in parts of Brazil.

Recent rains mean Brazil's soy harvest will be better than previously feared, while Argentina's crop will also be sizeable, Rabobank analyst Vitor Pistoia said.

Still, consultancy Patria Agronegocios

cut its forecast

for Brazilian soybean production by 5% to 143.18 million metric tons. (Reporting by Tom Polansek in Chicago; additional reporting by Peter Hobson in Canberra and Sybille de La Hamaide in Paris; editing by Varun H K, Sohini Goswami, David Goodman, Jonathan Oatis and Deepa Babington)