NYSE Group Inc. and the American Stock Exchange yesterday announced the execution of a definitive agreement for the NYSE to acquire the one-third ownership stake in the Securities Industry Automation Corp. held by Amex for approximately US$40 million.

Upon completion of the transaction, which is expected to close in November, NYSE Group will fully own SIAC. It currently owns two-thirds of SIAC.

“We view this as a strategic opportunity to assume greater control of a meaningful portion of our cost base that will allow us to drive improved efficiencies and growth,” said NYSE Group president and co-COO Jerry Putnam, who is also SIAC chairman and interim CEO. “Following the transaction, the American Stock Exchange will continue to be a customer of SIAC, although we expect them to reduce their usage of SIAC’s services as previously disclosed.”

“This marks another watershed moment for Amex’s march to technological rebirth. We are pleased with the cooperation that NYSE and the SIAC staff showed in helping to complete this transaction,” said Neal Wolkoff, chairman & CEO of Amex. “We look forward to a new and independent technology future for the Amex together with the launch of AEMISM, our new state-of-the-art electronic market platform.”