Form 8-K

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

 

FORM 8-K

 

CURRENT REPORT

Pursuant to Section 13 or 15(d) of

the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported):

March 28, 2007

 

COLUMBIA BANKING SYSTEM, INC.

(Exact name of registrant as specified in its charter)

 

Washington

(State or other jurisdiction of incorporation)

 

0-20288   91-1422237
(Commission File Number)   (IRS Employer Identification No.)

1301 A Street

Tacoma, WA 98402

(Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (253) 305-1900

 

(Former name or former address, if changed since last report.)

 

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligations of the registrant under any of the following provisions:

 

x Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

 

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

 

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

 

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

 

Item 1.01. Entry into a Material Definitive Agreement

On March 28, 2007, Columbia Banking System, Inc. (“Columbia”), entered into a Plan and Agreement of Merger (the “Merger Agreement”) with Mountain Bank Holding Company (“MBHC”). Under the terms of the Merger Agreement, MBHC will merge with and into Columbia, and MBHC’s bank subsidiary, Mt. Rainier National Bank, will merge with and into Columbia’s subsidiary, Columbia State Bank (the “Transaction”).

Effective at the time of the merger, each outstanding common share of MBHC will be exchanged for a unit of cash and Columbia common stock, the amount of which will be based on the price of Columbia’s stock. Consummation of the merger is subject to several conditions, including receipt of applicable regulatory approvals and approval by the shareholders of MBHC. For information regarding the terms of the Transaction, reference is made to the press release dated March 28, 2007, which is attached as Exhibit 99.1 and incorporated herein by reference.

 

Item 9.01. Financial Statements and Exhibits

 

  (d) Exhibits.

 

  99.1 Press Release dated March 28, 2007

 

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

 

Dated: March 28, 2007

   COLUMBIA BANKING SYSTEM, INC.
  By:  

/s/ Melanie J. Dressel

    Melanie J. Dressel
    President and Chief Executive Officer

 

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