The $869 million merger between Pinnacle Entertainment (NASDAQ:PNK) and Ameristar Casinos (UNKNOWN:ASCA.DL), announced back in December, hit a bit of a hiccup Tuesday, when both companies reported in SEC filings that they have received a "second request" from the Federal Trade Commission.

The FTC is reviewing Pinnacle's planned purchase of Ameristar for antitrust compliance under the Hart-Scott-Rodino Act. As the companies advised in their filing, "the effect of the second request is to extend the waiting period imposed by the HSR Act until 30 days after each company has substantially complied with the second request, unless that period is extended voluntarily by the companies or terminated sooner by the FTC."

To minimize the potential delay, Pinnacle and Ameristar say they "intend to expeditiously respond to the information request and to continue to work cooperatively with the FTC in connection with this review." For the time being, both companies are continuing to expect the transaction to close in Q2 or Q3 of 2013.