IBG's bid adds up to about $790 million, which is 6% above the unit's net regulatory capital. J.C. Flowers' bid was $768 million, just 3% above the unit's book value.
"We anxiously await the response of Refco," said Gary Mennitt, an attorney representing IBG.
Since the Refco scandal broke, clients have withdrawn about 40% of their money. The bids will be addressed at a Monday hearing in Bankruptcy court in New York.