UPDATE 1-Old National, First Financial start share offerings

* Old National to offer $150 mln of common shares

* First Financial to sell $50 mln of common shares

* Both cos looking at FDIC-assisted deals

Sept 21 (Reuters) - Old National Bancorp (ONB.N) and First Financial Holdings Inc (FFCH.O) will offer common shares worth $150 million and $50 million, respectively, with an eye on bidding for Federal Deposit Insurance Corp-assisted deals.

Evansville, Indiana-based Old National said the net proceeds from the offering would be used for general corporate purposes and to support growth, which may include acquisitions of assets and liabilities of failed or distressed financial institutions in FDIC-sponsored transactions.

Separately, Charleston, South Carolina-based First Financial said the net proceeds would also position the company for potential future redemption of the preferred stock issued to the U.S. Treasury under the Troubled Asset Relief Program Capital Purchase Program.

Both the companies said they plan to grant the underwriters a 30-day option to purchase up to an additional 15 percent of the shares offered to cover over-allotments.

Sandler O'Neill & Partners LP is the sole book-running manager for both the offerings.

Shares of Old National closed at $11.27 Friday on the New York Stock Exchange, while those of First Financial closed at $17.59 on Nasdaq. (Reporting by Abhinav Sharma in Bangalore; Editing by Anne Pallivathuckal)