UNITED STATES

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): May 24, 2017

FIRST INTERSTATE BANCSYSTEM, INC.

(Exact name of registrant as specified in its charter)

(406) 255-5390

(Registrant’s telephone number, including area code)

Not Applicable

(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 obligation of the registrant under any of the following provisions:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

(b)    On May 24, 2017, David H. Crum notified First Interstate BancSystem, Inc. (the “Company”) that he was retiring as a Director of the Company effective upon the adjournment of the Board of Directors’ meeting on July 20, 2017. His retirement is not related to a disagreement with the Company on any matter relating to the Company’s operations, policies or practices.

On May 24, 2017, the Company held its Annual Meeting of Shareholders (the “Annual Meeting”).

At the Annual Meeting, the following proposals were considered and voted on, and the final voting results for each proposal are set forth below:

1. Proposal to approve and adopt the Agreement and Plan of Merger, dated November 17, 2016, by and between the Company and Cascade Bancorp, pursuant to which Cascade Bancorp will merger with and into the Company.

2. Proposal to approve the amended and restated articles of incorporation of the Company.

3. Proposal to elect as directors the nominees proposed by the board of directors of the Company to three-year terms, or until their respective successors have been elected and qualified.

4. Proposal to approve a non-binding advisory resolution on executive compensation.

5. Proposal to approve a non-binding advisory vote on the frequency of future advisory votes on executive compensation.

6. Proposal to ratify the appointment of RSM US LLP as the independent registered public accounting firm for the Company for the year ending December 31, 2017.

7. Proposal to approve the amended and restated bylaws of the Company.

Because the merger agreement proposal was approved, a proposal to adjourn the Annual Meeting to solicit additional proxies if there were insufficient votes at the time of the Annual Meeting to approve the merger agreement proposal was not needed and, therefore, no vote was taken on that proposal.

On May 24, 2017, the Company and Cascade Bancorp issued a joint press release announcing the results of the Annual Meeting of the Company, the results of the Special Meeting of Cascade Bancorp, and the anticipated timing for completing the merger. A copy of the joint press release is filed as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated by reference into this Item 8.01.

SIGNATURE

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, hereunto duly authorized.