NYSE chief executive John Thain stepped forward to support Goldman Sachs Group Inc.’s role in the proposed acquisition of Archipelago Holdings Inc. by the New York Stock Exchange.

``Several members have asked about the role played by Goldman Sachs and the potential for conflicts,’’ Thain, a former Goldman president, and NYSE Chairman Marshall Carter wrote yesterday. ``Goldman was only involved in facilitating the transaction and bringing the two parties together.’’

Goldman advised both sides of the deal. The investment bank has a 15.5% stake in Archipelago and owns 21 out of 1,366 seats on the NYSE.

Goldman will be able to scoop in a nice sum in the acquisition. Archipelago announced that it plans to pay Goldman $3.5 million for advising on the transaction. In the letter dated April 15, disclosed by Archipelago in an SEC filing, Goldman is depicted as a facilitator of negotiations that also agreed to perform basic financial valuations.

In addition, the value of Goldman’s stake in the electronic platform has risen by about $77 million since the revelation of the deal by NYSE Chief Executive Officer John Thain. Goldman will own about 5.7 percent of the combined company that will get the name of NYSE Group Inc.

Goldman ``did not assume fiduciary responsibilities, nor did it negotiate the final aspects of the transaction on behalf of either the exchange or Archipelago,’’ Thain said in the letter.