UPDATE 3-Dow Chemical to launch $1.63 bln share offering

* Says to raise $1.63 billion through stock offering

* Also considering offering senior unsecured notes

* Shares down 3 percent in after market trade (Adds detail about offering, paragraph 5)

By Hezron Selvi

NEW YORK, May 5 (Reuters) - Dow Chemical Co (DOW.N) said it will sell about $1.63 billion of its common stock in a public offering as it works to pay down the debt load incurred with its acquisition of Rohm and Haas.

The company said it plans to raise about $1 billion from the shares and will use the proceeds to repay some of the $9.2 billion loan it used for its more than $15 billion takeover of Rohm and Haas.

The remaining $625 million will be paid to trusts created by members of the Haas Family and hedge fund Paulson & Co.

The investors are selling a portion of the $3 billion in preferred shares they received in the Rohm and Haas deal, which will be converted into common shares for the offering.

A $1.63 billion offering would mean the company would have to issue around 100 million shares if it were to do the offering today. That would be in addition to the roughly 925 million shares already outstanding.