FILE PHOTO - The ticker and trading information for Blackstone Group is displayed at the post where it is traded on the floor of the New York Stock Exchange (NYSE) April 4, 2016. REUTERS/Brendan McDermid

(Reuters) - U.S. private equity firm Blackstone Group LP said on Thursday it would buy a controlling stake in midstream energy company Tallgrass Energy LP for $3.3 billion.

Under the deal, Blackstone will acquire a 44 percent stake in Tallgrass Energy and take over the company’s general partner, Tallgrass Energy GP LLC.

Singapore's sovereign wealth fund, GIC, will also be a minority investor in the deal. (reut.rs/2CUzTUJ)

The deal will be financed by Blackstone’s planned $40 billion infrastructure fund, to which Saudi Arabia’s main sovereign wealth fund agreed last year to contribute up to $20 billion.

It will be the first deal since Blackstone started raising funds.

The transaction is expected to close in the first quarter of 2019.