PARSIPPANY, N.J. ( TheStreet) -- GenTek ( GETI) shares were rocketing nearly 40% in Monday trading following news that a unit of private equity shop American Securities was bringing GenTek into its fold. In a Monday morning press release, GenTek -- a New Jersey-based maker of chemical products and auto parts -- said it agreed to go private for around $411 million. The American Securities subsidiary will pay $38 per share in a tender offer for GenTek's common stock, which is a near 41% premium over Friday's closing price of $27. After the release, shares added $10.70 at $37.70 in the morning. The total transaction is being valued at $673 million, which includes the assumption of some $262 million in debt. -- Written by Sung Moss in New York Follow TheStreet.com on Twitter and become a fan on Facebook.