Nyse Euronext's proposed merger with Deutsche Börse has moved a step nearer after the Committee on Foreign Investment in the United States (CFIUS) waved through the deal.
CFIUS, which is chaired by the US department of the Treasury, reviews the national security implications for the country of foreign investment in companies.
It has now completed its review, concluding that there are no national security grounds on which to oppose the $9.4 billion merger.
The CFIUS clearance marks one more hurdle overcome by the two exchanges but they still need approval from several agencies on both sides of the Atlantic.
The biggest potential stumbling block is expected to come from European competition authorities concerned about how a merger would affect the derivatives market.
Duncan Niederauer, CEO, Nyse Euronext, says: "We are continuing to work with regulatory authorities to achieve the remaining approvals and deliver this compelling combination to shareholders, clients and partners."