Exhibit 99

First Interstate BancSystem First Quarter 2008 Financial Highlights            Three Months ended March 31, To our shareholders, First Interstate BancSystem is pleased to report first quarter (unaudited) 2008 2007 % Change 2008 net income to common shareholders of $17,307,000, or ^{(in thousands except per share data) $}2.14 per share, compared to $16,496,000, or $1.97 per share, OPERATING RESULTS            in first quarter 2007. 2008 first quarter earnings are the high- Net income $ 18,076 $ 16,496 9.6% est first quarter earnings reported in our history. Return on            Net income to common stockholders 17,307 16,496 4.9% average common equity was 15.82% in first quarter 2008, as            Diluted earnings per share 2.14 1.97 8.6% compared to 16.14% in first quarter 2007 and return on average            Dividends per share 0.65 1.02 -36.3% assets was 1.20% versus 1.37%. PERIOD END BALANCES            Quarterly Results Assets 6,284,356 4,959,855 26.7% Our financial performance for first quarter 2008 includes the Loans 4,384,346 3,363,981 30.3% results of the First Western Banks acquired January 10, 2008. Investment securities 1,141,850 984,245 16.0% As of the date of acquisition, the First Western Banks had as- Deposits 4,901,949 3,863,224 26.9% sets of $918,000,000, loans of $725,000,000 and deposits of Stockholders’ equity 504,452 421,617 19.6% $812,000,000. Common shares outstanding 7,885 8,183 -3.6% Net interest income increased 18% to $56,803,000 for first quar- QUARTERLY AVERAGES            ter 2008, as compared to the same period in 2007. Despite 27% Assets 6,065,208 4,884,328 24.2% growth in average earning assets, our net interest margin ratio Loans 4,246,302 3,322,149 27.8% decreased 17 basis points to 4.29% in first quarter 2008, as Investment securities 1,117,297 1,075,443 3.9% compared to first quarter 2007. This decrease is due, in part, to Deposits 4,700,927 3,680,205 33.2% the deployment of available funding into non-earning assets Stockholders’ equity 485,267 414,502 17.1% including premises, equipment, goodwill and core deposit intan- gible assets recorded as part of the First Western acquisition. In addition, interest free funding sources, including noninterest bearing deposits and equity, comprised a smaller percentage of our funding base during first quarter 2008, as compared to first benefits expenses and increases in occupancy costs. During quarter 2007, further compressing our net interest margin ratio. first quarter 2008, we recorded charges for impairment of mort- gage servicing rights of $3,552,000 as compared to $793,000 Our provisions for loan losses of $2,363,000 were 26% higher during first quarter 2007. Exclusive of expenses directly attribut-than first quarter 2007. This increase is primarily due higher able to the acquired entities, salary and benefits expense in-levels of internally classified loans combined with provisions creased $1,619,000, or 7%, as compared to first quarter 2007 related to the acquired banks. primarily due to inflationary wage increases and occupancy            expense increased $418,000, or 12%, primarily due to higher Noninterest income of $26,369,000 for first quarter 2008 was repairs, maintenance and depreciation expenses. $4,530,000, or 21%, higher than first quarter 2007. Approxi- mately 33% of the increase in 2008 was directly attributable to On April 8, 2008, we paid a $.65 dividend per common share. the acquired banks. In addition, d uring first quarter 2008, we            recorded a one-time gain on the mandatory redemption of Visa Our financial performance for the first quarter of 2008 is note-stock of $1,620,000 and a one-time gain of $1,083,000 from the worthy, especially in light of the challenges facing the banking release of escrowed funds related to the December 2006 sale of industry today. Our results confirm our confidence in the econo-our interest in iPay Technologies, LLC. The remaining improve- mies of Montana, Wyoming and South Dakota and in the abili-ment in noninterest income was primarily due to increases of ties of the talented and dedicated team of employees, officers $1,221,000 in income from the origination and sale of residential and directors who guide our company. real estate mortgage loans; $589,000 in debit and credit card            transaction fees, $407,000 in insurance commissions and $327,000 in wealth management revenues. These improve- ments offset a first quarter 2007 non-recurring gain of $1,100,000 on the sale of mortgage servicing rights. Noninterest expense of $53,155,000 was $10,243,000, or 24%, Lyle R. Knight            Terrill R. Moore higher than first quarter 2007. Approximately 55% of the in- President Executive Vice President crease in 2008 was directly attributable to the acquired banks. Chief Executive Officer            Chief Financial Officer The remaining increase was primarily due to additional charges            for impairment of mortgage servicing rights, higher salaries and

First Quarter 2008 Condensed Consolidated Statements of Income            Condensed Consolidated Balance Sheet            Three Months Ended            March 31, March 31, (unaudited) 2008 2007 (unaudited) 2008 2007 (in thousands, except per share data) (In thousands) ASSETS            Total interest income......... $ 91,109 $ 78,636 Cash and due from banks $ 231,241 $ 152,028 34,306 Federal funds sold. 47,018 162,515 Total interest expense .. 30,492 Interest bearing deposits .... 10,788 19,063 Net interest income 56,803 48,144 Investment securities ... 1,141,850 984,245 Provision for loan losses ..... 2,363 1,875 Loans..... 4,384,346 3,363,981 Net interest income after Less: allowance for loan losses 68,415 ..... 48,621 provision for loan losses .. 54,440 46,269 Net loans. 4,315,931 3,315,360 Noninterest income ..... 26,369 21,839 Premises & equipment, net 163,987.. 119,923 Noninterest expense ... 53,155 42,912 Accrued interest receivable 41,736.. 31,786 Income before taxes ... 27,654 25,196 Goodwill... 182,794 37,380 Income taxes .. 9,578 8,700 Core deposit intangible . 14,604 257 Net income ... 18,076 16,496 Mortgage servicing rights ... 18,872 20,359 Less: preferred stock dividends 769 .... Company owned life insurance 67,661........ 65,261 Net income to common stockholders $ 17,307 $ ... 16,496 Other assets... 47,874 51,678 Total Assets..... $ 6,284,356 $ 4,959,855 DATA PER COMMON SHARE: LIABILITIES AND STOCKHOLDERS’ EQUITY            Diluted EPS.. $ 2.14 $ 1.97 Dividends ... 0.65 1.02 Deposits... $ 4,901,949 $ 3,863,224 Book value... 63.97 51.52 Federal funds purchased .... 39,960 Tangible book value... 40.79 46.95 Securities sold under repurchase agreements. 535,990 568,042 Appraised value .. 83.50 * 89.00 ** Accrued interest payable .... 25,555 20,325 * Based on the latest independent appraised minority share valuation as of December 31, 2007, effective for transactions on or after February 15, 2008. Accounts payable & accrued 43,210expenses 33,952... ** Based on the latest independent appraised minority share valuation as of December 31, 2006, effective for transactions on or after February 15, 2007. Other borrowed funds... 12,030 220 Long — term debt... 97,495 11,237 Subordinated debentures ... 123,715 41,238 Total Liabilities. 5,779,904 4,538,238 Stockholders’ equity .... 504,452 421,617 Total Liabilities and Stockholders’ Equity $ 6,284,356 $ 4,959,855 Selected Ratios            Three Months Ended            March 31, (unaudited) 2008 2007 PERFORMANCE Return on average common equity 15.82%... 16.14% Return on average common equity excluding            DILUTED EARNINGS PER COMMON SHARE            other comprehensive income .... 15.74% 15.88% Return on average assets....... 1.20% 1.37% $2.50 Net interest margin, FTE... 4.29% 4.46% Efficiency ratio .... 63.91% 61.32% $2.00 CREDIT QUALITY (Period End) $1.50 Annualized provision for loan 0.22%losses 0.23%to average loans.. Annualized net charge offs to 0.07%average 0.09% loans ... $1.00 Allowance for loan losses to loans 1.56% 1.45%.. $0.50 Allowance for loan losses to non-accruing loans 134.19%....... 312.96% Non-accruing loans to total loans 1.16% .... 0 46% $0.00 1Q07 2Q07 3Q07 4Q07 1Q08 CAPITAL ADEQUACY & LIQUIDITY Leverage capital ratio .. 7.11% 8.04% Average loans to average deposits 90.33% .. 90.23% First Interstate BancSystem, Inc. P.O. Bo x 30918 Billings, Montana 59116 (406) 255-5390 www.firstinterstatebank.com