Exhibit 99

Third Quarter 2009 Condensed Consolidated Statements of Income Three Months Ended Nine Months Ended September 30, September 30, (Unaudited) 2009 2008 2009 2008 (In thousands, except per share data) Total interest income $ 82,325 $ 89,928 $ 245,356 $ 269,105 Total interest expense 21,026 29,234 65,804 93,237 Net interest income 61,299 60,694 179,552 175,868 Provision for loan losses 10,500 5,636 31,800 13,320 Net interest income after provision for loan losses 50,799 55,058 147,752 162,548 Noninterest income 25,000 24,389 78,480 76,012 Noninterest expense 57,376 55,189 162,558 158,034 Income before taxes 18,423 24,258 63,674 80,526 Income taxes 6,105 8,362 21,332 27,928 Net income 12,318 15,896 42,342 52,598 Less: preferred stock dividends 862 863 2,559 2,484 Net income to common stockholders $ 11,456 $ 15,033 $ 39,783 $ 50,114 DATA PER COMMON SHARE: Diluted EPS $ 1.46 $ 1.89 $ 5.02 $ 6.25 Dividends 0.45 0.65 1.55 1.95 Book value to common stockholders 66.26 59.85 Tangible book value to common stockholders 38.87 31.78 Appraised value 60.00 77.00* ** * Based on the latest independent appraised minority share valuation as of June 30, 2009, effective for transactions on or after August 17, 2009. ** Based on the independent appraised minority share valuation as of June 30, 2008, effective for transactions transactions on or after August 13, 2008. Selected Ratios Three Months Ended Nine Months Ended September 30, September 30, (Unaudited) 2009 2008 2009 2008 PERFORMANCE Return on average common equity 8.98% 13.18% 10.66% 14.87% Return on average assets 0.71% 0.98% 0.84% 1.12% Net interest margin, FTE 4.00% 4.30% 4.05% 4.29% Efficiency ratio 66.51% 64.87% 63.01% 62.74% CREDIT QUALITY (Period End) Annualized provision for loan losses to average loans 0.91% 0.40% Annualized net charge offs to average loans 0.49% 0.09% Allowance for loan losses to total loans 2.21% 1.62% Allowance for loan losses to non-accruing loans 84.77% 91.51% Nonperforming assets to total loans & other real estate owned 3.38% 1.96% CAPITAL ADEQUACY & LIQUIDITY Leverage capital ratio 7.96% 7.06% Loan to deposit ratio at period end 81.05% 94.23% Condensed Consolidated Balance Sheets September 30, (Unaudited) 2009 2008 (In thousands) ASSETS Cash and due from banks $ 216,532 $ 203,114 Federal funds sold 294,279 37,317 Interest bearing deposits 1,631 1,296 Investment securities 1,297,845 1,030,570 Loans 4,606,454 4,744,675 Less: allowance for loan losses 101,748 77,094 Net loans 4,504,706 4,667,581 Premises & equipment, net 197,261 171,990 Goodwill 183,673 187,297 Company owned life insurance 70,748 68,790 Accrued interest receivable 38,742 42,571 Other real estate owned 31,875 6,025 Mortgage servicing rights 20,224 21,870 Core deposit intangible assets 11,082 13,322 Other assets 54,620 58,270 Total Assets $ 6,923,218 $ 6,510,013 LIABILITIES AND STOCKHOLDERS' EQUITY Deposits $ 5,683,130 $ 5,035,344 Federal funds purchased - 69,420 Securities sold under repurchase agreements.. 391,336 510,457 Accrued interest payable 19,145 19,704 Accounts payable & accrued expenses 51,951 39,423 Other borrowed funds 5,766 102,257 Long-term debt 77,491 84,695 Subordinated debentures 123,715 123,715 Total Liabilities 6,352,534 5,985,015 Stockholders' equity 570,684 524,998 Total Liabilities and Stockholders' Equity $ 6,923,218 $ 6,510,013 P.O. Box 30918 _ Billings, Montana 59116 _ (406) 255-5390 www.firstinterstatebank.com First Interstate BancSystem, Inc.

First Interstate BancSystem, Third Quarter 2009 To our shareholders, First Interstate BancSystem is pleased to announce third quarter 2009 net income to common shareholders of $11,456,000, or $1.46 per diluted share, as compared to $15,033,000, or $1.89 per diluted share, for third quarter 2008. Return on average common equity was 8.98% in third quarter 2009 compared to 13.18% in third quarter 2008, and return on average assets was 0.71% compared to 0.98%. During third quarter 2009, we continued to actively manage credit quality and provide ample reserves for potential loan losses. We have been diligent in our efforts to maintain our allowance for loan losses at a level we feel is sufficient to provide for estimated losses inherent in our loan portfolio. We recorded provisions for loan losses of $10,500,000 during third quarter 2009 bringing our year-to-date provision to $31,800,000, as compared to year-to-date provisions of $13,320,000 through September 30, 2008. The allowance for loan losses increased to 2.21% of total loans as of September 30, 2009 from 1.83% as of December 31, 2008 and 1.62% as of September 30, 2008. Nonperforming assets were 3.38% of total loans and other real estate owned as of September 30, 2009 compared to 1.96% as of September 30, 2008. Net loan charge-offs increased to 0.49% of average loans annualized during the first nine months of 2009 from 0.09% during the first nine months of 2008. In addition, during third quarter 2009 we recorded losses on other real estate owned of $5,160,000, the majority of which related to a decline in the estimated market value of one real estate development property. The net interest margin declined to 4.00% during third quarter 2009, as compared to 4.04% during second quarter 2009 and 4.30% during third quarter 2008. Additional liquidity supporting strong deposit demand combined with weak demand for loans and higher levels of nonperforming assets adversely impacted our net interest margin ratio. Our loan to deposit ratio currently stands at 81%, down from 94% just one year ago. During the first nine months of 2009, our focus on balancing growth to improve liquidity resulted in higher federal funds sold balances, which produce lower yields than other interest earnings assets. In addition, interest-free and low cost funding sources, such as demand deposits, federal funds purchased and short-term borrowings comprised a smaller percentage of our total funding base, which further compressed our net FTE interest margin. Low interest rates in 2009 spurred an increase in residential mortgage loan origination. Income from the origination and sale of residential mortgages increased 84% to $5,090,000 during third quarter 2009 compared to the same period in 2008. Income from the origination and sale of residential mortgages increased 171% to $25,682,000 for the nine months ended September 30, 2009 compared to the same period in 2008. We have retained the servicing of most of the residential mortgages we originate. During third quarter 2009, we expensed mortgage servicing rights impairment of $296,000, as compared to $1,640,000 during third quarter 2008. During the first nine months of 2009, we recorded a net reversal of impairment of $6,969,000 compared to net impairment expense of $895,000 during the same period in 2008. In May 2009, the FDIC levied a special assessment applicable to all insured depository institutions as part of its plan to replenish the FDIC insurance fund. This special assessment together with changes in fee assessment rates in 2009 substantially increased our FDIC insurance expense. FDIC insurance expense totaled $2,377,000 during third quarter 2009 compared to $904,000 during third quarter 2008 and for the nine months ended September 30, 2009, our FDIC insurance expense was $9,741,000 compared to $1,813,000 during the same period in 2008. Higher FDIC insurance expenses and losses on other real estate owned were partially offset by a one-time gain of $2,128,000 on the sale of our Class B Visa common stock. During third quarter 2009, we successfully completed the merger of the First Western Banks into First Interstate Bank. We are pleased to be serving the communities of western South Dakota as First Interstate Bank. Financial Highlights Three Months ended September 30, (Unaudited) 2009 2008 % Change (In thousands, except per share data) OPERATING RESULTS Net income $ 12,318 $ 15,896 -22.5% Net income to common stockholders 11,456 15,033 -23.8% Diluted earnings per share 1.46 1.89 -22.8% Dividends per share 0.45 0.65 -30.8% PERIOD END BALANCES Assets 6,923,218 6,510,013 6.3% Loans 4,606,454 4,744,675 -2.9% Investment securities 1,297,845 1,030,570 25.9% Deposits 5,683,130 5,035,344 12.9% Stockholders' equity 570,684 524,998 8.7% Common shares outstanding 7,859 7,937 -1.0% QUARTERLY AVERAGES Assets 6,893,844 6,424,429 7.3% Loans 4,623,749 4,672,200 -1.0% Investment securities 1,171,740 1,031,446 13.6% Deposits 5,593,024 4,944,992 13.1% Stockholders' equity 555,984 503,867 10.3% Common shares outstanding 7,806 7,805 0.0% We are pleased to report that our recent stock offering generated $3,770,000 of additional capital. On October 7, 2009, we paid dividends of $0.45 per common share. Our Board of Directors, together with management, has been evaluating our capital structure and needs as part of our ongoing business planning. Several financing alternatives for enhancing our capital and equity position are currently being considered, including a private equity offering, debt issuance and other funding transactions. As part of these alternatives, the Board is giving consideration to an initial public offering which would eliminate our need to conduct and fund quarterly stock repurchases and may enhance the value of our common stock. We will continue to evaluate our financing opportunities and steps are being taken to prepare the Company to pursue any one of these alternatives. Any decision regarding a financing transaction, and our ability to complete such a transaction, will depend on prevailing market conditions and other factors. As we continue to face many economic challenges, particularly the ongoing loss of jobs nationally and regionally and declining real estate values, our conservative approach has allowed us to maintain a strong balance sheet and continued profitability. We have met our strategic goal of building capital and have vastly improved our liquidity. We will continue to focus on improving earnings and managing credit quality in the upcoming quarters. Lyle R. Knight, our President and Chief Executive Officer, has agreed to delay his retirement, previously scheduled to occur in early 2011, until March 31, 2012. We thank our dedicated team of employees and directors for their continued commitment to our success. Lyle R. Knight President Chief Executive Officer Terrill R. Moore Executive Vice President Chief Financial Officer