CHICAGO, Dec 12 (Reuters) - Spot basis bids for corn were mostly down and soy bids held steady in the U.S. Midwest on Thursday as farmers sold some of their crop in storage before the end of the year.

* The corn basis fell at an Ohio elevator, an Illinois processor and an Indiana ethanol plant. The basis increased at an Iowa processor.

* Buyers have been pressured by tight profit margins.

* The U.S. Department of Agriculture reported net export sales of U.S. corn at 946,900 tons, below trade expectations of 1,100,000 to 1,900,000 tons.

* The U.S. Department of Agriculture reported net export sales of 1,173,800 tons, below trade estimates of 1,500,000 to 2,200,000 tons.

* Most-active corn futures Cv1 traded down 5 cents at $4.43 per bushel as of 1650 GMT (10:50 CT).

* Most-active soy futures Sv1 were down 4-1/4 cents at $9.91-1/4 per bushel as of 1650 GMT.

Basis values are quoted against CBOT futures in cts/bu:

NOTE: 0 = Option price, UNC = Unchanged, UNQ = Unquoted

NC = Not comparable, DP = Delayed price, N/A = Not available,

F = January, H = March, K = May, N = JulyQ = August, U = September, X = November, Z = December

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LINKS: 0#USCSHGRN-PM

For U.S. forward basis spreadsheets, please click:

CORN/BASIS, SOYA/BASIS, WHEAT/BASIS, MILO/BASIS

- CBOT corn report COR/

- CBOT soybean report SOY/C

- CBOT wheat report WHE/C

- U.S. grain barge freight values BG/US

- U.S. Midwest cash grain PM GRA/PM

- U.S. CIF/FOB Gulf Grain GRA/F

(Reporting by Heather Schlitz; Editing by Alexandra Hudson)

((Heather.Schlitz@thomsonreuters.com;))