The Nasdaq Stock Market Inc. says anti-trust regulators are seeking more information about its proposed acquisition of Instinet Group Inc.

The exchange announced today that the Department of Justice has requested more information as part of an investigation under the Hart-Scott-Rodino Antitrust Improvements Act of its pending acquisition of Instinet.

The request suspends the 30-day period in which the DOJ is required to conclude its investigation and make a determination on the Nasdaq acquisition of Instinet. A new 30-day period will commence once Nasdaq and Instinet substantially complete their replies to the request, it notes.

That said, the companies say they expected to receive this request, and continue to work with the DOJ. And, they don’t expect it will affect the anticipated timing of the merger closing.