The sources, speaking on condition of anonymity because they were not authorized to discuss the matter publicly, said Buffett's conglomerate Berkshire Hathaway was the 'Company A' bidder disclosed in a regulatory filing by ICE on Monday.
Mr Buffett's assistant could not immediately comment on the report. NYSE Euronext declined to comment. The news was first reported by CNBC's David Faber.
ICE agreed to buy NYSE Euronext late last month for $8.2 billion following about two months of talks.
Before the deal closed, NYSE's board of directors instructed the company's bankers to pursue alternatives, according to the ICE filing with the U.S. Securities and Exchange Commission.
Bankers from Perella Weinberg approached 'Company A' on November 25, the filing said. On November 28, 'Company A' presented an offer that was less than the ICE bid and was conditioned on the sale of NYSE Euronext's European derivatives business for a minimum price.
At a NYSE board meeting December 12 and 13, Perella Weinberg indicated that it was still working with 'Company A' but that the bidder had not improved the offer. There was no further mention of the unnamed bidder in the filing.
Had Berkshire done the deal, it would have been somewhat small by Mr Buffett's standards. He spent much of 2012 trying to do deals in the $20 billion range, and even said at one point that he might have to look at doing a $30 billion deal this year.
Copyright @ Thomson Reuters 2013