REFILE-Late CBOT soy futures sell-off prompts complaints

(Refiles, adds dropped word "soybeans" in first paragraph)

By Julie Ingwersen

CHICAGO, Dec 28 (Reuters) - Traders at the Chicago Board of Trade complained on Friday after a sharp sell-off in the electronic market sent soybean prices plunging during the final minute of trading, causing a big disparity between closing prices in the pit and the electronic platform.

A CME Group CME.N spokeswoman said all trades in CBOT soybean futures would stand, fending off the complaints.

The spot January soybean futures contract SF8 fell to $11.65 per bushel on the electronic platform in the final minute, down 47-1/2 cents at the close.

However, in the open-outcry pit, the contract's low was $12.02-1/4, and it settled officially at $12.07-3/4, down 4-3/4 cents for the day.

Settlement prices are based on trade in the pit, although the majority of trade has migrated to the electronic platform since side-by-side trading was introduced in August 2006.

There were similarly large disparities between the closing price on the electronic platform and the official settlement price in deferred soybean contracts.

"It's where the market settled. No trades were busted. All trades stand," CME Group spokeswoman Mary Haffenberg said.

She noted that the late plunge came during a period of thin trade, which can add to price volatility.

Uncertainty about the price disparity between the electronic market and the official settlements caused ripples in the cash markets.

Dealers at some elevators and processors in the U.S. Midwest were not accepting any soybean sales, and buyers in the CIF market at the U.S. Gulf pulled their bids. (Reporting by Julie Ingwersen; Editing by David Gregorio)