NEW YORK (

TheStreet

) -- Activist investor

Carl Icahn

has purchased a nearly 10% stake in

Dynegy

(DYN)

, setting the stage for a buyout battle with private equity player

Blackstone

(BX) - Get Report

over the energy company.

A 13D filed with the Securities and Exchange Commission early on Tuesday disclosed that various funds associated with Icahn had purchased an aggregate 12 million shares, or 9.95% of total shares outstanding for $57.5 million.

In the filing, the investors said they believed shares of Dynegy to be undervalued and that they may from time to time "seek to have conversations" with Dynegy about its proposed agreement to merge with Blackstone Group. The filing further stated that the investors "do not believe the consideration agreed to in the proposed merger is adequate."

Last week, hedge fund

Seneca Capital

also disclosed a 9.3% stake in the company. The new stakeholders are likely to exert greater pressure on Blackstone to raise its offer price of $4.50 a share for Dynegy.

Dynegy was rising 0.8% to $4.75 in premarket trading.

-- Written by Shanthi Venkataraman in New York

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