GHL Acquisition Corp. and Iridium Holdings, a leading provider of mobile voice and data satellite services, signed a definitive agreement under which they plan to combine.

The proceeds of the transaction will enable Iridium to be debt-free and well-positioned to develop its next generation satellite constellation, “Iridium NEXT.”

GHL Acquisition is a special-purpose acquisition company sponsored by Greenhill & Co. Inc., which raised approximately $400 million in gross proceeds earlier this year. GHL is approximately 17.5 percent owned by Greenhill & Co.

The transaction values Iridium at around $591 million. Following completion of the deal, the combined enterprise will be renamed Iridium Communications Inc. and will apply for listing on the NASDAQ.

Click here for details about the transaction.