Duke Energy and Cinergy have filed an application with the US Federal Energy Regulatory Commission (FERC), seeking approval for their $9 billion all-stock merger by early 2006.

In a merger deal announced in May, Duke Energy agreed to acquire Cinergy for $9 billion in stock, creating a utility giant with 5.4 million natural gas and electricity customers.

In addition to FERC’s approval, the merger requires the approval of shareholders and regulatory approvals from the Nuclear Regulatory Commission, Securities and Exchange Commission, and the Department of Justice among others.

The new company, which will be called Duke Energy Corp, will own or operate 54GWe of generation capacity domestically along with significant gas assets. However, it has also been speculated that Duke Energy may split off its natural gas assets to become a purely electric player.