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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

___________________________________________________________________________________________________________________________________________________

FORM 10-Q

_____________________________________________________________________________________________________________________________________________________

☒ Quarterly report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

For the quarterly period ended September 30, 2025

☐ Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

For the transition period from to

COMMISSION FILE NUMBER 001-34653

________________________________________________________________________________________________________

FIRST INTERSTATE BANCSYSTEM, INC.

(Exact name of registrant as specified in its charter)

________________________________________________________________________________________________________


Delaware		81-0331430
(State or other jurisdiction of incorporation or organization)		(IRS Employer Identification No.)

401 North 31st Street
Billings,	MT	59101
(Address of principal executive offices)		(Zip Code)

Registrant’s telephone number, including area code: (406) 255-5311

N/A

(Former name, former address and former fiscal year, if changed since last report)

_________________________________________________________________________________________________

Securities registered pursuant to Section 12(b) of the Act:


Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, $0.00001 par value	FIBK	NASDAQ

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files.) Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer

☒

Accelerated filer

☐

Non-accelerated filer

☐

Smaller reporting company

☐

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. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

Indicate the number of shares outstanding of each of the registrant’s classes of common stock, as of the latest practicable date:


October 31, 2025 – Common stock			102,890,614

Quarterly Report on Form 10-Q


	FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES
	Index
	September 30, 2025
		Page Nos.
	Part I - Financial Information

Item 1.	Financial Statements (Unaudited)

	Consolidated Balance Sheets	3

	Consolidated Statements of Income	4

	Consolidated Statements of Comprehensive Income	5

	Consolidated Statements of Changes in Stockholders’ Equity	6

	Consolidated Statements of Cash Flows	8

	Notes to Unaudited Consolidated Financial Statements	10

Item 2.	Management's Discussion and Analysis of Financial Condition and Results of Operations	42

Item 3.	Quantitative and Qualitative Disclosures about Market Risk	60

Item 4.	Controls and Procedures	62

	Part II - Other Information

Item 1.	Legal Proceedings	63

Item 1A.	Risk Factors	63

Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	64

Item 3.	Defaults Upon Senior Securities	64

Item 4.	Mine Safety Disclosures	64

Item 5.	Other Information	64

Item 6.	Exhibits	65

Signatures		66

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

(In millions, except share data)

(Unaudited)


	September 30, 2025		December 31, 2024
Assets
Cash and due from banks	$	382.7	$	378.0
Interest bearing deposits in banks	1,066.4		518.5
Federal funds sold	0.1		0.1
Total cash and cash equivalents	1,449.2		896.6
Investment securities:
Available-for-sale, at fair value	4,895.5		5,057.1
Held-to-maturity (estimated fair values of $2,185.4 at September 30, 2025 and $2,358.6 at December 31, 2024)	2,410.3		2,687.5
Total investment securities	7,305.8		7,744.6
FHLB and FRB stock, at cost	106.8		177.4
Loans held for sale ($0.6 and $0.9 of which is recorded at fair value at September 30, 2025 and December 31, 2024, respectively)	305.6		0.9
Loans held for investment, net of deferred fees and costs	15,834.4		17,844.9
Allowance for credit losses	(205.8)		(204.1)
Net loans held for investment	15,628.6		17,640.8
Goodwill	1,100.9		1,100.9
Company-owned life insurance	520.2		513.0
Premises and equipment, net of accumulated depreciation	415.1		427.2
Other intangibles, net of accumulated amortization	56.6		66.8
Accrued interest receivable	106.6		116.8
Mortgage servicing rights, net of accumulated amortization	23.8		25.7
Other real estate owned	3.4		4.3
Deferred tax asset, net	66.7		118.4
Other assets	243.6		304.0
Total assets	$	27,332.9	$	29,137.4
Liabilities and Stockholders’ Equity
Deposits:
Noninterest bearing	$	5,555.7	$	5,797.6
Interest bearing	17,049.3		17,218.0
Total deposits	22,605.0		23,015.6
Securities sold under repurchase agreements	485.2		523.9
Accounts payable and accrued expenses	436.0		378.9
Accrued interest payable	42.4		47.0

Other borrowed funds	—		1,567.5
Long-term debt	146.2		132.2
Allowance for credit losses on off-balance sheet credit exposures	6.3		5.2

Subordinated debentures held by subsidiary trusts	163.1		163.1
Total liabilities	23,884.2		25,833.4
Stockholders’ equity:
Preferred stock, $0.00001 par value; 100,000 shares authorized at September 30, 2025 and December 31, 2024; zero issued and outstanding, respectively	—		—
Common stock and additional paid-in-capital, $0.00001 par value; 150,000,000 shares authorized at September 30, 2025 and December 31, 2024; 103,967,257 and 104,585,964 shares issued and outstanding, respectively	2,439.3		2,459.5
Retained earnings	1,213.5		1,166.4
Accumulated other comprehensive loss, net	(204.1)		(321.9)
Total stockholders’ equity	3,448.7		3,304.0
Total liabilities and stockholders’ equity	$	27,332.9	$	29,137.4

See accompanying notes to unaudited consolidated financial statements.

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME

(In millions, except per share data)

(Unaudited)


	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Interest income:
Interest and fees on loans	$	233.8	$	258.9	$	714.8	$	763.8
Interest and dividends on investment securities:
Taxable	47.8		60.7		148.7		187.5
Exempt from federal taxes	0.7		0.7		2.1		2.1
Interest and dividends on FHLB and FRB stock	1.3		2.8		6.3		9.4
Interest on deposits in banks	8.4		4.9		20.9		13.9

Total interest income	292.0		328.0		892.8		976.7
Interest expense:
Interest on deposits	76.9		84.2		227.3		244.2
Interest on securities sold under repurchase agreements	1.2		1.4		3.5		5.6
Interest on other borrowed funds	0.4		32.0		26.2		99.4
Interest on long-term debt	3.8		1.6		8.2		10.3
Interest on subordinated debentures held by subsidiary trusts	2.9		3.3		8.6		9.9
Total interest expense	85.2		122.5		273.8		369.4
Net interest income	206.8		205.5		619.0		607.3
Provision for credit losses	—		19.8		19.7		34.1
Net interest income after provision for credit losses	206.8		185.7		599.3		573.2
Noninterest income:
Payment services revenues	16.8		18.7		51.7		55.7
Mortgage banking revenues	1.5		1.7		4.7		5.1
Wealth management revenues	10.4		9.6		29.9		28.2
Service charges on deposit accounts	7.0		6.6		20.5		19.0
Other service charges, commissions, and fees	2.1		2.2		6.5		6.5


Other income	5.9		7.6		13.5		16.6

Total noninterest income	43.7		46.4		126.8		131.1
Noninterest expense:
Salaries and wages	66.2		70.9		199.8		202.4
Employee benefits	18.2		19.7		56.1		55.9
Outsourced technology services	14.9		14.6		42.4		42.2
Occupancy, net	13.2		11.8		40.3		35.8
Furniture and equipment	5.3		5.2		15.5		15.4
OREO expense, net	—		—		0.5		4.0
Professional fees	6.1		4.2		17.3		16.1
FDIC insurance premiums	3.7		5.2		12.0		19.2


Other intangibles amortization	3.4		3.6		10.2		11.0
Other expenses	26.9		24.2		79.5		74.5


Total noninterest expense	157.9		159.4		473.6		476.5
Income before income tax	92.6		72.7		252.5		227.8
Provision for income tax	21.2		17.2		59.2		53.9
Net income	$	71.4	$	55.5	$	193.3	$	173.9

Earnings per common share (Basic)	$	0.69	$	0.54	$	1.87	$	1.69
Earnings per common share (Diluted)	$	0.69	$	0.54	$	1.87	$	1.69

See accompanying notes to unaudited consolidated financial statements.

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(In millions)

(Unaudited)


	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Net income	$	71.4	$	55.5	$	193.3	$	173.9
Other comprehensive income, before tax:
Investment securities available for sale:
Change in net unrealized gains during the period	38.1		158.5		153.5		134.6


Net change in unamortized gains (losses) on available-for-sale securities transferred into held-to-maturity	0.1		(0.2)		—		(0.5)
Cash flow hedges:
Change in unrealized gains (losses) on derivatives	—		12.4		1.9		(10.1)
Reclassification adjustment for derivatives net losses included in net income	0.2		3.1		1.6		11.2


Other comprehensive income, before tax	38.4		173.8		157.0		135.2
Deferred tax expense related to other comprehensive income	(9.6)		(43.2)		(39.2)		(33.6)
Other comprehensive income, net of tax	28.8		130.6		117.8		101.6
Comprehensive income, net of tax	$	100.2	$	186.1	$	311.1	$	275.5

See accompanying notes to unaudited consolidated financial statements.

Table of Contents


FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY (In millions, except share and per share data) (Unaudited)
	Three Months Ended September 30,
	Common stock		Retained earnings		Accumulated other comprehensive loss		Total stockholders’ equity
Balance at June 30, 2025	$	2,463.5	$	1,191.2	$	(232.9)	$	3,421.8


Net income	—		71.4		—		71.4

Other comprehensive income, net of tax expense	—		—		28.8		28.8
Common stock transactions:
844,426 common shares purchased and retired	(27.5)		—		—		(27.5)
3,706 common shares issued	—		—		—		—
2,308 non-vested common shares issued	—		—		—		—
68,508 non-vested common shares forfeited or canceled	—		—		—		—



Stock-based compensation expense	3.3		—		—		3.3
Common stock cash dividends declared ($0.47 per share)	—		(49.1)		—		(49.1)
Balance at September 30, 2025	$	2,439.3	$	1,213.5	$	(204.1)	$	3,448.7

	Common stock		Retained earnings		Accumulated other comprehensive loss		Total stockholders’ equity
Balance at June 30, 2024	$	2,453.9	$	1,156.9	$	(385.5)	$	3,225.3


Net income	—		55.5		—		55.5

Other comprehensive income, net of tax expense	—		—		130.6		130.6
Common stock transactions:
3,972 common shares purchased and retired	(0.1)		—		—		(0.1)

4,881 non-vested common shares issued	—		—		—		—
31,664 non-vested common shares forfeited or canceled	—		—		—		—



Stock-based compensation expense	3.6		—		—		3.6
Common stock cash dividends declared ($0.47 per share)	—		(49.1)		—		(49.1)
Balance at September 30, 2024	$	2,457.4	$	1,163.3	$	(254.9)	$	3,365.8
See accompanying notes to unaudited consolidated financial statements.

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY (In millions, except share and per share data) (Unaudited)
	Nine Months Ended September 30,
	Common stock		Retained earnings		Accumulated other comprehensive loss		Total stockholders’ equity
Balance at December 31, 2024	$	2,459.5	$	1,166.4	$	(321.9)	$	3,304.0


Net income	—		193.3		—		193.3

Other comprehensive income, net of tax expense	—		—		117.8		117.8
Common stock transactions:
952,074 common shares purchased and retired	(30.7)		—		—		(30.7)
39,058 common shares issued	—		—		—		—
482,597 non-vested common shares issued	—		—		—		—
188,288 non-vested common shares forfeited or canceled	—		—		—		—



Stock-based compensation expense	10.5		—		—		10.5
Common stock cash dividends declared ($1.41 per share)	—		(146.2)		—		(146.2)
Balance at September 30, 2025	$	2,439.3	$	1,213.5	$	(204.1)	$	3,448.7

	Common stock		Retained earnings		Accumulated other comprehensive loss		Total stockholders’ equity
Balance at December 31, 2023	$	2,448.9	$	1,135.1	$	(356.5)	$	3,227.5
Cumulative change related to the adoption of ASU 2023-02	—		1.2		—		1.2
Adjusted balance at January 1, 2024	2,448.9		1,136.3		(356.5)		3,228.7
Net income	—		173.9		—		173.9

Other comprehensive income, net of tax expense	—		—		101.6		101.6
Common stock transactions:
49,420 common shares purchased and retired	(1.2)		—		—		(1.2)

742,979 non-vested common shares issued	—		—		—		—
105,322 non-vested common shares forfeited or canceled	—		—		—		—



Stock-based compensation expense	9.7		—		—		9.7
Common stock cash dividends declared ($1.41 per share)	—		(146.9)		—		(146.9)
Balance at September 30, 2024	$	2,457.4	$	1,163.3	$	(254.9)	$	3,365.8
See accompanying notes to unaudited consolidated financial statements.

Table of Contents


FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF CASH FLOWS
(In millions)	Nine Months Ended September 30,
(Unaudited)	2025		2024
Cash flows from operating activities:
Net income	$	193.3	$	173.9
Adjustments to reconcile net income from operations to net cash provided by operating activities:
Provision for credit losses	19.7		34.1
Net loss on disposal of premises and equipment	5.1		—
Depreciation and amortization	36.4		41.4
Net premium amortization on investment securities	(0.1)		0.9

Realized and unrealized net gains on mortgage banking activities	(1.5)		(1.4)

Net losses and write-downs of OREO and other assets pending disposal	0.5		3.8

Net loss on extinguishment of debt	0.7		—


Valuation allowance for loans held-for-sale	6.1		—
Deferred taxes	11.9		6.6
Net increase in cash surrender value of company-owned life insurance	(7.6)		(10.7)
Stock-based compensation expense	10.5		9.7
Originations of mortgage loans held for sale	(62.6)		(131.4)
Proceeds from sales of mortgage loans held for sale	64.0		130.7
Gain on sale of consumer credit card loans	(4.3)		—
Changes in operating assets and liabilities:
Decrease in accrued interest receivable	10.2		1.8
Decrease in other assets	68.3		10.9
(Decrease) increase in accrued interest payable	(4.6)		35.5
Decrease in accounts payable and accrued expenses	(107.7)		(46.0)
Net cash provided by operating activities	238.3		259.8
Cash flows from investing activities:
Purchases of investment securities	(652.0)		(102.2)


Proceeds from sales, maturities, and pay-downs of investment securities:
Held-to-maturity	280.4		470.0
Available-for-sale	1,115.8		539.4
Net sales (purchases) of FHLB and FRB stock	70.6		67.7

Proceeds from company-owned life insurance settlements	0.3		2.1
Proceeds from sales of consumer credit card loans	81.3		—
Net change in loans held for investment	1,608.3		226.5
Proceeds from sale of OREO	0.7		12.9

Capital expenditures, net of sales	(19.5)		(16.4)
Net cash provided by investing activities	2,485.9		1,200.0
Cash flows from financing activities:
Net decrease in deposits	(410.6)		(459.0)
Net decrease in securities sold under repurchase agreements	(38.7)		(225.5)
Net decrease in other borrowed funds	(1,567.5)		(773.0)

Repayments of long-term debt	(100.1)		(0.1)
Proceeds on long-term debt	—		266.5

Payment of debt issuance costs	(2.8)		—
Proceeds from issuance of subordinated notes	125.0		—


Purchase and retirement of common stock	(30.7)		(1.2)
Dividends paid to common stockholders	(146.2)		(146.9)
Net cash used in financing activities	(2,171.6)		(1,339.2)
Net (decrease) increase in cash and cash equivalents	552.6		120.6
Cash and cash equivalents at beginning of period	896.6		578.0
Cash and cash equivalents at end of period	$	1,449.2	$	698.6

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES CONSOLIDATED STATEMENTS OF CASH FLOWS (continued)
(In millions)	Nine Months Ended September 30,
(Unaudited)	2025		2024

Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	$	24.4	$	12.1
Cash paid during the period for interest expense	278.2		333.9
Supplemental disclosures of noncash investing and financing activities:

Right-of-use assets, net obtained in exchange for operating lease liabilities	$	7.5	$	1.1



Transfer of held for investment loans to held-for-sale, net	311.1		—
Transfer of loans to other real estate owned	0.2		4.6

Transfer of premises and equipment to held-for-sale	13.2		—
Capitalization of internally originated mortgage servicing rights	0.5		0.5

See accompanying notes to unaudited consolidated financial statements.

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

(1) BASIS OF PRESENTATION

The accompanying unaudited consolidated financial statements of First Interstate BancSystem, Inc., and its consolidated subsidiaries, including its wholly-owned subsidiary, First Interstate Bank (“FIB”) (collectively, the “Company”) contain all adjustments (all of which are of a normal recurring nature) necessary to present fairly the financial position of the Company at September 30, 2025 and December 31, 2024, the results of operations, changes in stockholders’ equity, and cash flows for each of the three and the nine months ended September 30, 2025 and 2024, in conformity with U.S. generally accepted accounting principles (“GAAP”). The balance sheet information at December 31, 2024 is derived from audited consolidated financial statements. The unaudited consolidated financial statements have been prepared in conformity with the required interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X; and therefore, do not include all of the information and footnotes required by GAAP for a complete set of financial statements. Certain reclassifications, none of which were material, have been made to conform the Company’s prior year financial statements to the financial statements as of September 30, 2025. These reclassifications did not change previously reported net income, financial condition, cash flows, or stockholders’ equity.

The Company has identified one reporting unit and one operating segment, community banking, which encompasses commercial and consumer banking services to serve a similar base of clients utilizing company-wide offerings of similar products and services managed through similar processes and platforms offered to individuals, businesses, municipalities, and other entities, whose primary sources of revenue are interest income on loans, investment securities and other interest-earning assets and fee income earned on its products and services. Its expenses consist of interest expense on deposits and borrowed funds, provision for credit losses, other operating expenses and income taxes, as further described below. The Company manages its business activities on a consolidated basis.

The Company’s chief operating decision maker (“CODM”) is its Chief Executive Officer who is charged with management of the Company and is responsible for the evaluation of operating performance and decision making about the allocation of capital and resources.

The CODM regularly assesses performance of the single operating and reporting segment and decides how to allocate resources based on net income calculated on the same basis as is net income reported in the Company’s consolidated statements of income. The CODM is also regularly provided with expense information at a level consistent with that disclosed in the Company’s consolidated statements of income.

The Company’s principal expenses include: (i) interest expense on deposit accounts and other borrowings; (ii) salaries and employee benefits; (iii) information technology and communication costs primarily associated with maintaining loan and deposit functions; (iv) furniture, equipment, and occupancy expenses for maintaining our facilities; (v) professional fees, including FDIC insurance assessments; (vi) income tax expense; (vii) provisions for credit losses; (viii) intangible amortization; (ix) other real estate owned expenses; and (x) other segment expenses including legal expenses, advertising and promotion, donations, credit card rewards expense, fees associated with originating and closing loans, insurance, and other expenses necessary to support our employees and service our clients. See the consolidated financial statements for other financial information regarding the Company’s operating segment.

The accounting policies of the segment are the same as those described in "Note 1 - Summary of Significant Accounting Policies" of the Company's Annual Report on Form 10-K for the year ended December 31, 2024.

These unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024, which includes a description of significant accounting policies. Operating results for the three and the nine months ended September 30, 2025 are not necessarily indicative of the results that may be expected for the year ending December 31, 2025.

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

(2) INVESTMENT SECURITIES

The amortized cost and the approximate fair values of investment securities are summarized as follows:


September 30, 2025	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	246.1	$	—	$	(10.3)	$	235.8
State, county, and municipal securities	248.6		—		(30.4)		218.2
Obligations of U.S. government agencies	207.1		—		(5.2)		201.9
U.S. agency commercial mortgage-backed securities	941.7		1.0		(42.4)		900.3
U.S. agency residential mortgage-backed securities	1,446.4		3.1		(78.7)		1,370.8
U.S. agency collateralized mortgage obligations	1,027.5		1.3		(72.5)		956.3
Private mortgage-backed securities	199.2		—		(21.2)		178.0
Collateralized loan obligation	671.0		0.9		—		671.9
Corporate securities	172.0		—		(9.7)		162.3

Total	$	5,159.6	$	6.3	$	(270.4)	$	4,895.5


September 30, 2025	Amortized Cost(1)		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
U.S. Treasury notes	$	—	$	—	$	—	$	—
State, county, and municipal securities	175.1		0.2		(19.8)		155.5
Obligations of U.S. government agencies	464.7		0.1		(40.7)		424.1
U.S. agency commercial mortgage-backed securities	363.1		—		(21.7)		341.4
U.S. agency residential mortgage-backed securities	976.4		0.1		(94.4)		882.1
U.S. agency collateralized mortgage obligations	391.8		0.6		(48.7)		343.7
Corporate securities	39.9		—		(1.3)		38.6

Total	$	2,411.0	$	1.0	$	(226.6)	$	2,185.4
(1) Amortized cost presented above is net of an allowance for credit losses of $0.7 million and includes $6.4 million of unamortized gains and $14.3 million of unamortized losses related to the 2021 and 2022 transfer of securities from available-for-sale to held-to-maturity, respectively.


December 31, 2024	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-Sale:
U.S. Treasury notes	$	245.0	$	—	$	(18.1)	$	226.9
State, county, and municipal securities	252.0		—		(40.0)		212.0
Obligations of U.S. government agencies	224.1		—		(10.8)		213.3
U.S. agency commercial mortgage-backed securities	1,057.2		0.1		(74.5)		982.8
U.S. agency residential mortgage-backed securities	1,301.2		0.4		(125.8)		1,175.8
U.S. agency collateralized mortgage obligations	1,156.9		0.6		(106.6)		1,050.9
Private mortgage-backed securities	218.1		—		(27.6)		190.5
Collateralized loan obligation	770.7		1.3		—		772.0
Corporate securities	249.6		—		(16.7)		232.9

Total	$	5,474.8	$	2.4	$	(420.1)	$	5,057.1

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)


December 31, 2024	Amortized Cost(1)		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Held-to-Maturity:
U.S. Treasury notes	$	99.8	$	—	$	(0.4)	$	99.4
State, county, and municipal securities	176.3		0.2		(26.7)		149.8
Obligations of U.S. government agencies	470.1		—		(59.9)		410.2
U.S. agency commercial mortgage-backed securities	374.9		—		(33.4)		341.5
U.S. agency residential mortgage-backed securities	1,082.5		—		(140.7)		941.8
U.S. agency collateralized mortgage obligations	427.8		—		(66.1)		361.7
Corporate securities	57.0		—		(2.8)		54.2

Total	$	2,688.4	$	0.2	$	(330.0)	$	2,358.6
(1) Amortized cost presented above is net of an allowance for credit losses of $0.9 million and includes $8.0 million of unamortized gains and $15.9 million of unamortized losses related to the 2021 and 2022 transfer of securities from available-for-sale to held-to-maturity, respectively.

The following tables show the gross unrealized losses and fair values of available-for-sale investment securities and the length of time individual investment securities have been in an unrealized loss position as of September 30, 2025 and December 31, 2024.


	Less than 12 Months				12 Months or More				Total
September 30, 2025	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	—	$	—	$	235.8	$	(10.3)	$	235.8	$	(10.3)
State, county, and municipal securities	—		—		216.5		(30.4)		216.5		(30.4)
Obligations of U.S. government agencies	3.1		—		195.7		(5.2)		198.8		(5.2)
U.S. agency commercial mortgage-backed securities	—		—		866.4		(42.4)		866.4		(42.4)
U.S. agency residential mortgage-backed securities	71.5		(0.5)		980.9		(78.2)		1,052.4		(78.7)
U.S. agency collateralized mortgage obligations	6.6		—		901.1		(72.5)		907.7		(72.5)
Private mortgage-backed securities	—		—		177.9		(21.2)		177.9		(21.2)
Collateralized loan obligation	30.0		—		—		—		30.0		—
Corporate securities	—		—		153.3		(9.7)		153.3		(9.7)

Total	$	111.2	$	(0.5)	$	3,727.6	$	(269.9)	$	3,838.8	$	(270.4)


	Less than 12 Months				12 Months or More				Total
December 31, 2024	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
Available-for-Sale:
U.S. Treasury notes	$	—	$	—	$	226.8	$	(18.1)	$	226.8	$	(18.1)
State, county, and municipal securities	—		—		210.1		(40.0)		210.1		(40.0)
Obligations of U.S. government agencies	3.6		—		206.2		(10.8)		209.8		(10.8)
U.S. agency commercial mortgage-backed securities	38.1		(0.4)		934.9		(74.1)		973.0		(74.5)
U.S. agency residential mortgage-backed securities	33.7		(1.5)		1,086.2		(124.3)		1,119.9		(125.8)
U.S. agency collateralized mortgage obligations	20.5		(0.3)		987.1		(106.3)		1,007.6		(106.6)
Private mortgage-backed securities	—		—		190.4		(27.6)		190.4		(27.6)
Collateralized loan obligation	10.0		—		—		—		10.0		—
Corporate securities	27.5		(0.5)		205.5		(16.2)		233.0		(16.7)

Total	$	133.4	$	(2.7)	$	4,047.2	$	(417.4)	$	4,180.6	$	(420.1)

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The Company determines the allowance for credit losses on both available-for-sale and held-to-maturity investment securities by a discounted cash flow approach when needed, using each security’s effective interest rate at the time of purchase or upon acquisition. The allowance for credit losses for available-for-sale investment securities is measured as the amount by which an investment security’s amortized cost exceeds the net present value of expected future cash flows, however, the amount of credit losses is limited to the amount of a security’s unrealized loss. The allowance for credit loss on held-to-maturity investment securities is representative of current expected credit losses that management expects to be incurred over the life of the investment and established through a charge to provision for credit losses in current period earnings. For held-to-maturity investment securities, the Company has the intent and ability to hold these investment securities to maturity.

The investment securities portfolio primarily contains securities that are guaranteed by a sovereign entity or are generally considered to have non-credit related risks, such as interest rate risk or liquidity factors. The Company considers whether the securities are issued by the federal government or its agencies and whether downgrades by bond rating agencies have occurred.

As of September 30, 2025 and December 31, 2024, the Company had 633 and 670 individual available-for-sale investment securities, respectively, that were in an unrealized loss position, which was related primarily to fluctuations in current interest rates. As of September 30, 2025, the Company does not intend to sell nor is it more likely than not the Company will be required to sell any available-for-sale securities with unrealized losses.

The Company had no allowance for credit losses on available-for-sale investment securities as of September 30, 2025 and December 31, 2024.

On a quarterly basis, the Company refreshes the credit quality indicator of each held-to-maturity security. As of September 30, 2025 and December 31, 2024, the held-to-maturity portfolio is primarily composed of investment grade or better securities. The Company had a $0.7 million and a $0.9 million allowance for credit losses for held-to-maturity corporate and state, county, and municipal investment securities as of September 30, 2025 and December 31, 2024, respectively.

As of September 30, 2025 and December 31, 2024, the Company had $23.2 million and $29.6 million, respectively, of accrued interest receivable from investment securities on the consolidated balance sheets. Accrued interest receivable is presented as a separate line item on the consolidated balance sheets and is not included in the carrying value of our securities.

During the three months ended September 30, 2025 and 2024, there were no gross realized gains or losses on the disposition of available-for-sale investment securities.

The following schedule represents the amortized cost of debt securities by contractual maturity except for maturities of mortgage-backed securities, which have been adjusted to reflect shorter maturities based upon estimated prepayments of principal.


	Available-for-Sale				Held-to-Maturity
September 30, 2025	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
Within one year	$	106.2	$	105.3	$	8.3	$	8.4
After one year but within five years	1,233.5		1,187.1		573.6		547.4
After five years but within ten years	989.6		919.8		327.9		297.3
After ten years	2,830.3		2,683.3		1,501.2		1,332.3
Total	$	5,159.6	$	4,895.5	$	2,411.0	$	2,185.4

As of September 30, 2025, the Company held investment securities callable within one year having amortized costs and estimated fair values of $682.2 million and $654.1 million, respectively. These investment securities are primarily included in the “after five year” categories in the table above.

As of September 30, 2025 and December 31, 2024, the Company had securities with carrying values of $2,877.5 million and $3,460.2 million, respectively, for investment securities pledged to secure public deposits, derivatives, and securities sold under repurchase agreements that had estimated fair values as of September 30, 2025 and December 31, 2024, of $2,664.0 million and $3,092.6 million, respectively. All securities sold under repurchase

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

agreements are with clients and mature on the next banking day. The Company retains possession of the underlying securities sold under repurchase agreements.

As of September 30, 2025 and December 31, 2024, the Company held $106.8 million and $177.4 million, respectively, in equity securities primarily in a combination of Federal Reserve Bank and Federal Home Loan Bank (“FHLB”) stocks, which are restricted nonmarketable securities acquired to meet regulatory requirements and related to outstanding borrowings. These securities are carried at cost.

(3) LOANS HELD FOR SALE

Residential mortgage loans that the Company originated with the intent to sell are recorded at fair value. The following table presents (i) residential mortgage loans recorded at fair value and (ii) other loans held for sale at lower of cost or market by class of receivable related to the sale of the Arizona and Kansas branches (which was pending as of September 30, 2025), net of a $6.1 million valuation allowance, in addition to the pending sale of approximately $645.0 million in deposits, for the dates indicated:


	September 30, 2025		December 31, 2024
Real estate:
Commercial	$	214.6	$	—
Construction	0.2		—
Residential	0.7		—
Residential mortgage, at fair value	0.6		0.9
Agricultural	15.4		—
Total real estate	231.5		0.9
Consumer:

Direct and advance lines	0.8		—

Total consumer	0.8		—
Commercial	68.2		—
Agricultural	5.1		—
Total loans held for sale	$	305.6	$	0.9

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

(4) LOANS HELD FOR INVESTMENT

The following table presents loans by class of receivable and portfolio segment as of the dates indicated:


	September 30, 2025		December 31, 2024
Real estate:
Commercial	$	8,496.4	$	9,263.2
Construction	960.8		1,244.6
Residential	2,136.0		2,191.6
Agricultural	623.0		701.1
Total real estate	12,216.2		13,400.5
Consumer:
Indirect	540.3		725.0
Direct and advance lines	134.3		134.0
Credit card	—		77.6
Total consumer	674.6		936.6
Commercial	2,447.4		2,829.4
Agricultural	495.5		687.9
Other, including overdrafts	10.2		1.6
Loans held for investment	15,843.9		17,856.0
Deferred loan fees and costs	(9.5)		(11.1)
Loans held for investment, net of deferred fees and costs	15,834.4		17,844.9
Allowance for credit losses	(205.8)		(204.1)
Net loans held for investment	$	15,628.6	$	17,640.8

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

Allowance for Credit Losses

The following tables represent, by loan portfolio segments, the activity in the allowance for credit losses for loans held for investment:


Three Months Ended September 30, 2025	Beginning Balance		Provision for (reversal of) Credit Losses		Loans Charged-Off(2)		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate	$	148.7	$	1.7	$	(0.8)	$	1.5	$	151.1
Consumer	12.0		1.9		(3.8)		2.2		12.3
Commercial	42.9		(4.9)		(2.1)		0.7		36.6
Agricultural	6.0		(0.2)		—		—		5.8
Total allowance for credit losses	$	209.6	$	(1.5)	$	(6.7)	$	4.4	$	205.8

Nine Months Ended September 30, 2025	Beginning Balance		Provision for Credit Loss		Loans Charged-Off(2)		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate	$	139.4	$	9.2	$	(4.3)	$	6.8	$	151.1
Consumer	16.8		4.7		(14.1)		4.9		12.3
Commercial	38.9		3.3		(7.2)		1.6		36.6
Agricultural	9.0		1.6		(4.9)		0.1		5.8
Total allowance for credit losses	$	204.1	$	18.8	$	(30.5)	$	13.4	$	205.8

Three Months Ended September 30, 2024	Beginning Balance		Provision for (reversal of) Credit Losses		Loans Charged-Off(2)		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate	$	139.7	$	18.3	$	(22.2)	$	0.2	$	136.0
Consumer	18.5		1.5		(4.1)		1.3		17.2
Commercial	69.2		(0.1)		(2.5)		0.2		66.8
Agricultural	5.4		0.3		(0.3)		—		5.4
Total allowance for credit losses	$	232.8	$	20.0	$	(29.1)	$	1.7	$	225.4

Nine Months Ended September 30, 2024	Beginning Balance		Provision for (reversal of) Credit Losses		Loans Charged-Off(2)		Recoveries Collected		Ending Balance
Allowance for credit losses (1)
Real estate	$	160.1	$	10.3	$	(35.5)	$	1.1	$	136.0
Consumer	13.0		12.5		(11.9)		3.6		17.2
Commercial	50.2		23.2		(8.7)		2.1		66.8
Agricultural	4.4		1.0		(0.3)		0.3		5.4
Total allowance for credit losses	$	227.7	$	47.0	$	(56.4)	$	7.1	$	225.4

(1) Amounts presented exclude the ACL related to unfunded commitments and investment securities. The allowance for credit losses related to unfunded commitments and investment securities are included in the “Financial Instruments with Off-Balance Sheet Risk” Note and “Investment Securities” Note, respectively.
(2) Loans, or portions thereof, are charged-off against the ACL when management believes the collectability of the principal is unlikely, or, with respect to consumer installment loans, according to an established delinquency schedule.

Collateral-Dependent Loans

A collateral-dependent loan relies substantially on the operation or sale of the collateral securing the loan for repayment. A loan may become collateral-dependent when foreclosure is probable or the borrower is experiencing financial difficulty and its sources of repayment become inadequate over time.

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The following tables present the principal balance of collateral-dependent loans by class of receivable as of the dates indicated:


	Collateral Type
As of September 30, 2025	Business Assets		Real Property		Other		Total
Real estate:
Commercial	$	—	$	71.9	$	—	$	71.9
Construction	—		3.8		—		3.8
Residential	—		2.7		—		2.7
Agricultural	—		23.1		—		23.1
Total real estate	—		101.5		—		101.5
Commercial	23.6		7.5		1.4		32.5
Agricultural	13.1		0.5		—		13.6
Total collateral-dependent loans	$	36.7	$	109.5	$	1.4	$	147.6



	Collateral Type
As of December 31, 2024	Business Assets		Real Property		Other		Total
Real estate:
Commercial	$	—	$	47.3	$	—	$	47.3
Construction	—		3.2		—		3.2
Residential	—		2.7		—		2.7
Agricultural	—		1.8		—		1.8
Total real estate	—		55.0		—		55.0
Commercial	20.3		1.1		0.8		22.2
Agricultural	—		20.3		0.1		20.4
Total collateral-dependent loans	$	20.3	$	76.4	$	0.9	$	97.6

Loans are considered past due if the required principal and interest payments have not been received 30 days or more past the contractual payment due date. Loans classified in the following table as 90 days or more past due continue to accrue interest. The following tables present the contractual aging of the Company’s recorded principal balance of loans by class of receivable as of the dates indicated:



	30 - 59		60 - 89		90 or more
	Days		Days		Days		Total Loans		Current		Non-accrual		Total
As of September 30, 2025	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)(2)(3)		Loans
Real estate:
Commercial	$	5.0	$	0.2	$	—	$	5.2	$	8,417.0	$	74.2	$	8,496.4




Construction	0.3		—		—		0.3		956.3		4.2		960.8
Residential	2.1		1.1		—		3.2		2,116.7		16.1		2,136.0
Agricultural	2.4		—		—		2.4		593.7		26.9		623.0
Total real estate	9.8		1.3		—		11.1		12,083.7		121.4		12,216.2
Consumer:
Indirect	6.0		2.2		—		8.2		527.3		4.8		540.3
Direct and advance lines	0.7		0.5		—		1.2		132.5		0.6		134.3
Credit card	—		—		—		—		—		—		—
Total consumer	6.7		2.7		—		9.4		659.8		5.4		674.6
Commercial	5.3		1.6		0.6		7.5		2,399.9		40.0		2,447.4
Agricultural	1.1		—		—		1.1		479.6		14.8		495.5
Other, including overdrafts	—		—		—		—		10.2		—		10.2
Loans held for investment	$	22.9	$	5.6	$	0.6	$	29.1	$	15,633.2	$	181.6	$	15,843.9

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)



	30 - 59		60 - 89		90 or more
	Days		Days		Days		Total Loans		Current		Non-accrual		Total
As of December 31, 2024	Past Due		Past Due		Past Due		Past Due		Loans		Loans (1)(2)(3)		Loans
Real estate:
Commercial	$	4.9	$	2.8	$	—	$	7.7	$	9,200.1	$	55.4	$	9,263.2




Construction	3.7		—		—		3.7		1,237.6		3.3		1,244.6
Residential	6.6		2.7		0.4		9.7		2,166.5		15.4		2,191.6
Agricultural	7.6		2.8		—		10.4		685.4		5.3		701.1
Total real estate	22.8		8.3		0.4		31.5		13,289.6		79.4		13,400.5
Consumer:
Indirect	8.4		2.6		0.7		11.7		709.4		3.9		725.0
Direct and advance lines	0.6		0.2		0.3		1.1		132.3		0.6		134.0
Credit card	0.7		0.5		1.0		2.2		75.4		—		77.6
Total consumer	9.7		3.3		2.0		15.0		917.1		4.5		936.6
Commercial	11.2		3.0		0.6		14.8		2,781.1		33.5		2,829.4
Agricultural	2.4		2.8		—		5.2		661.8		20.9		687.9
Other, including overdrafts	—		—		—		—		1.6		—		1.6
Loans held for investment	$	46.1	$	17.4	$	3.0	$	66.5	$	17,651.2	$	138.3	$	17,856.0

(1) As of September 30, 2025 and December 31, 2024, none of our non-accrual loans were earning interest income. Additionally, $2.0 million and $3.5 million interest income was recognized on non-accrual loans during the three and the nine months ended September 30, 2025, respectively, and $1.0 million and $1.8 million interest income was recognized on non-accrual loans during the three and the nine months ended September 30, 2024, respectively. There were $0.4 million and $2.9 million in reversals of accrued interest during the three and the nine months ended September 30, 2025, respectively, and $0.4 million and $2.4 million in reversals of accrued interest during the three and the nine months ended September 30, 2024, respectively.

(2) As of September 30, 2025 and December 31, 2024, there were approximately $101.0 million and $56.9 million, respectively, of non-accrual loans for which there was no related allowance for credit loss, as these loans had sufficient collateral securing the loan for repayment.

(3) As of September 30, 2025, there were approximately $13.0 million, $5.5 million, and $88.6 million of non-accrual loans that were 30-59 days past due, 60-89 days past due, and 90 days or more past due, respectively. As of December 31, 2024, there were approximately $13.5 million, $6.2 million, and $40.5 million of non-accrual loans that were 30-59 days past due, 60-89 days past due, and 90 days or more past due, respectively.

Modifications to Borrowers Experiencing Financial Difficulty

Modifications of loans are made in the ordinary course of business and are completed on a case-by-case basis through negotiation with the borrower in connection with the ongoing loan collection processes. Loan modifications are made to provide payment relief to borrowers experiencing financial difficulty.

From time to time, we may modify certain loans to borrowers who are experiencing financial difficulty. In some cases, these modifications may result in new loans. Loan modifications to borrowers experiencing financial difficulty may be in the form of principal forgiveness, an interest rate reduction, an other-than-insignificant payment delay, a term extension, or a combination thereof, among other things.

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The following tables present the amortized cost basis of loans, by class and by type of modification, at September 30, 2025 and 2024 that were both experiencing financial difficulty and modified during the periods indicated. The percentage of the principal balance of loans that were modified to borrowers in financial distress as compared to the principal balance of each class of receivable is also presented below:


Three Months Ended September 30, 2025	Principal Forgiveness		Term Extension		Term Extension and Interest Rate Reduction		Total		% of Total Class of Loans Held for Investment (1)
Real estate:
Commercial	$	—	$	2.3	$	—	$	2.3	0.03	%
Construction	—		1.7		—		1.7		0.18

Agricultural	—		12.1		2.8		14.9		2.39
Total real estate	—		16.1		2.8		18.9		0.15





Commercial	—		20.4		—		20.4		0.83
Agricultural	—		3.7		—		3.7		0.75

Loans held for investment (2)	$	—	$	40.2	$	2.8	$	43.0	0.27

Nine Months Ended September 30, 2025
Real estate:
Commercial	$	—	$	14.5	$	0.8	$	15.3	0.18	%
Construction	—		1.9		—		1.9		0.20
Residential	—		0.3		0.1		0.4		0.02
Agricultural	—		12.1		2.8		14.9		2.39
Total real estate	—		28.8		3.7		32.5		0.27





Commercial	—		24.8		0.2		25.0		1.02
Agricultural	—		6.0		—		6.0		1.21

Loans held for investment (2)	$	—	$	59.6	$	3.9	$	63.5	0.40


Three Months Ended September 30, 2024	Principal Forgiveness		Term Extension		Term Extension and Interest Rate Reduction		Total		% of Total Class of Loans Held for Investment (1)
Real estate:
Commercial	$	—	$	0.5	$	—	$	0.5	0.01	%
Construction	—		1.9		—		1.9		0.15

Agricultural	—		6.5		—		6.5		0.89
Total real estate	—		8.9		—		8.9		0.07





Commercial	—		0.9		0.5		1.4		0.05
Agricultural	—		21.4		—		21.4		3.10

Loans held for investment (2)	$	—	$	31.2	$	0.5	$	31.7	0.18

Nine Months Ended September 30, 2024
Real estate:
Commercial	$	—	$	14.7	$	—	$	14.7	0.16	%
Construction	—		1.9		—		1.9		0.15
Residential	—		0.1		0.3		0.4		0.02
Agricultural	—		12.1		—		12.1		1.67
Total real estate	—		28.8		0.3		29.1		0.22





Commercial	—		14.4		0.5		14.9		0.51
Agricultural	—		23.2		22.2		45.4		6.58

Loans held for investment (2)	$	—	$	66.4	$	23.0	$	89.4	0.50

(1) Based on the principal balance as of period end, divided by the period end principal balance of the corresponding class of receivables.

(2) As of September 30, 2025 and 2024, the Company excluded $0.7 million and $1.1 million, respectively, in accrued interest from the amortized cost of the identified loans.

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FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The following tables present the financial effect of the loan modifications presented above to borrowers experiencing financial difficulty during the periods indicated:



				Term Extension and Interest Rate Reduction
Three Months Ended September 30, 2025	Principal Forgiveness		Weighted-Average Months of Term Extension	Weighted-Average Months of Term Extension	Weighted-Average Interest Rate Reduction
Real estate:
Commercial	$	—	7.7	0.0	—	%
Construction	—		12.0	0.0	—

Agricultural	—		12.6	4.0	0.3
Total real estate	—





Commercial	—		4.9	0.0	—
Agricultural	—		7.2	0.0	—

Loans held for investment (1)	$	—

Nine Months Ended September 30, 2025
Real estate:
Commercial	$	—	13.2	13.3	0.9	%
Construction	—		7.4	0.0	—
Residential	—		22.3	84.8	2.2
Agricultural	—		12.6	4.0	0.3
Total real estate	—





Commercial	—		6.4	20.7	0.8
Agricultural	—		7.3	0.0	—

Loans held for investment (1)	$	—



				Term Extension and Interest Rate Reduction
Three Months Ended September 30, 2024	Principal Forgiveness		Weighted-Average Months of Term Extension	Weighted-Average Months of Term Extension	Weighted-Average Interest Rate Reduction
Real estate:
Commercial	$	—	5.9	0.0	—	%
Construction	—		4.0	0.0	—

Agricultural	—		7.7	0.0	—
Total real estate	—





Commercial	—		5.3	59.0	0.8
Agricultural	—		3.9	0.0	—

Loans held for investment (1)	$	—

Nine Months Ended September 30, 2024
Real estate:
Commercial	$	—	6.8	0.0	—	%
Construction	—		4.0	0.0	—
Residential	—		11.0	31.2	3.4
Agricultural	—		7.4	0.0	—
Total real estate	—





Commercial	—		7.7	9.2	1.0
Agricultural	—		4.1	55.2	1.1

Loans held for investment (1)	$	—

(1) Balances based on loan original contractual terms.

Table of Contents

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The Company monitors the performance of loan modifications to borrowers experiencing financial difficulty to understand the effectiveness of its modification efforts. Of the accruing loans that were modified during the twelve-months ended September 30, 2025 and 2024, there were $0.8 million and $0.5 million of loans classified as past due 30 days or more, respectively, with the remaining accruing loans performing in accordance with the modified terms and classified as current at September 30, 2025 and 2024. Of the non-accrual loans that were modified during the twelve-months ended September 30, 2025 and 2024, there were $10.5 million and $9.2 million of loans classified as past due 30 days or more, respectively, with the remaining non-accrual loans performing in accordance with the modified terms and classified as current at September 30, 2025 and 2024.

There were no commitments to lend additional funds related to the loan modifications to borrowers experiencing financial difficulty during the three months ended September 30, 2025 and 2024.

There were $2.1 million and $1.3 million of payment defaults on these loans subsequent to their modifications during the twelve-months ended September 30, 2025 and 2024. The Company considers a payment default to occur when the loan is 90 days or more past due or the loan is placed on non-accrual status after the modification. The Company monitors the performance of modified loans on an ongoing basis. In the event of subsequent default, the allowance for credit losses continues to be reassessed based on an individual evaluation of each loan. The modifications made during the periods presented did not significantly impact the Company’s determination of the allowance for credit losses.

Credit Quality Indicators

As part of the on-going and continuous monitoring of the credit quality of the Company’s loan portfolio, management tracks internally assigned risk classifications of loans based on relevant information about the ability of borrowers to service their debt. The factors considered by the Company include, among other factors, the borrower’s current financial information, historical payment experience, credit documentation, public information, and current economic trends. The Company analyzes loans individually to classify the credit risk of the loans. This analysis generally includes loans with an outstanding balance greater than $1.0 million, which are generally considered non-homogeneous loans, such as commercial loans and commercial real estate loans. This analysis is performed no less than on an annual basis, depending upon the size of exposure and the contractual obligations governing the borrower’s financial reporting frequency. Homogeneous loans, including small business loans, are typically monitored by payment performance. The Company internally risk rates its loans in accordance with a Uniform Classification System developed jointly by the various bank regulatory agencies. The Uniform Classification System defines three broad categories of criticized assets, which the Company uses as credit quality indicators in addition to the 6 Pass ratings in its 10-point rating scale:

Special Mention — includes loans that exhibit a potential weakness in financial condition, loan structure, or documentation that warrants management’s close attention. If not promptly corrected, the potential weaknesses may result in deterioration of the repayment prospects for the loan or of the institution’s credit position at some future date.

Substandard — includes loans that are inadequately protected by the current net worth and paying capacity of the borrower which have well-defined weaknesses that jeopardize the liquidation of the debt. Although the primary source of repayment for a substandard loan may not currently be sufficient, collateral or other sources of repayment are sufficient to satisfy the debt.

Doubtful — includes loans that exhibit pronounced weaknesses based on currently existing facts, conditions, and values to a point where collection or liquidation for full repayment is highly questionable and improbable. Doubtful loans are required to be placed on non-accrual status and are assigned specific loss exposure.

Loans not meeting the criteria above that are analyzed individually as part of the above-described process are considered pass-rated loans. A pass-rated loan can be assets where there is virtually no credit risk, such as cash secured loans with funds on deposit with the Bank. Pass-rated loans also include loans that are on our watch lists; these loans are currently performing but are subject to closer monitoring due to certain risk factors or emerging weaknesses that could, if not corrected, result in future deterioration of repayment capacity. These loans do not meet the criteria for classification as Special Mention or a criticized asset, but are included on the bank’s internal watch list to ensure proactive management and early identification of potential credit issues.

Table of Contents

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The Company evaluates the credit quality and loan performance for the allowance for credit losses of the following class of receivables by origination year using the origination date or the loan’s subsequent renewal or modification date based on the aforementioned risk scale as of and for the periods ended:


	September 30, 2025
	Term Loans Amortized Cost Basis by Origination Year
	2025		2024		2023		2022		2021		Prior		Revolving Loans Amortized Cost Basis		Revolving Loans Converted To Term		Total
Commercial real estate:
Pass	$	734.7	$	1,041.1	$	1,154.3	$	1,457.5	$	1,146.4	$	2,136.1	$	67.0	$	9.4	$	7,746.5
Special mention	170.4		92.4		16.7		37.9		77.6		110.3		0.1		—		505.4
Substandard	24.5		39.5		41.1		26.3		37.4		49.2		0.2		—		218.2
Doubtful	1.9		2.8		5.7		15.9		—		—		—		—		26.3
Total	931.5		1,175.8		1,217.8		1,537.6		1,261.4		2,295.6		67.3		9.4		8,496.4

Construction real estate:
Pass	225.2		271.4		113.9		185.6		30.7		24.0		82.1		—		932.9
Special mention	6.4		1.0		0.2		0.1		—		—		—		—		7.7
Substandard	1.8		4.9		—		10.1		1.0		0.1		0.2		—		18.1
Doubtful	—		1.3		—		—		0.8		—		—		—		2.1
Total	233.4		278.6		114.1		195.8		32.5		24.1		82.3		—		960.8

Agricultural real estate:
Pass	58.9		83.2		40.9		111.0		83.7		139.0		15.7		—		532.4
Special mention	9.1		10.5		3.5		3.4		8.6		12.3		1.1		—		48.5
Substandard	16.4		0.8		6.5		2.3		5.3		10.8		—		—		42.1

Total	84.4		94.5		50.9		116.7		97.6		162.1		16.8		—		623.0

Commercial:
Pass	211.9		329.8		256.7		297.0		242.7		284.9		625.1		7.3		2,255.4
Special mention	8.6		22.4		4.2		2.3		3.9		0.2		37.7		—		79.3
Substandard	8.0		11.6		7.8		23.9		4.0		1.9		44.2		0.2		101.6
Doubtful	1.5		2.4		0.5		6.3		0.4		—		—		—		11.1
Total	230.0		366.2		269.2		329.5		251.0		287.0		707.0		7.5		2,447.4

Agricultural:
Pass	62.6		41.8		19.3		29.3		10.3		6.8		246.1		—		416.2
Special mention	13.1		3.3		2.8		2.8		0.6		—		33.3		—		55.9
Substandard	1.6		3.4		0.7		0.1		—		0.5		6.9		—		13.2
Doubtful	5.5		0.1		2.6		—		—		—		2.0		—		10.2
Total	$	82.8	$	48.6	$	25.4	$	32.2	$	10.9	$	7.3	$	288.3	$	—	$	495.5

Table of Contents

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)


	December 31, 2024
	Term Loans Amortized Cost Basis by Origination Year
	2024		2023		2022		2021		2020		Prior		Revolving Loans Amortized Cost Basis		Revolving Loans Converted To Term		Total
Commercial real estate:
Pass	$	1,208.5	$	1,340.2	$	1,909.1	$	1,344.1	$	1,069.7	$	1,778.3	$	74.1	$	109.8	$	8,833.8
Special mention	78.4		17.5		15.8		16.1		4.9		79.2		0.6		9.8		222.3
Substandard	81.5		12.1		22.0		37.3		10.2		43.5		0.5		—		207.1

Total	1,368.4		1,369.8		1,946.9		1,397.5		1,084.8		1,901.0		75.2		119.6		9,263.2

Construction:
Pass	438.0		233.0		320.2		76.5		17.3		20.9		124.8		1.8		1,232.5
Special mention	2.1		—		6.4		—		—		—		—		—		8.5

Doubtful	3.6		—		—		—		—		—		—		—		3.6
Total	443.7		233.0		326.6		76.5		17.3		20.9		124.8		1.8		1,244.6

Agricultural real estate:
Pass	118.6		53.0		104.7		107.9		66.0		144.1		33.4		0.5		628.2
Special mention	1.1		0.2		6.8		6.1		8.5		0.7		—		—		23.4
Substandard	12.9		8.2		19.7		3.4		4.4		0.9		—		—		49.5

Total	132.6		61.4		131.2		117.4		78.9		145.7		33.4		0.5		701.1

Commercial:
Pass	438.8		353.0		375.9		316.0		165.9		255.2		767.3		8.9		2,681.0
Special mention	3.9		13.9		3.1		2.2		6.2		0.6		19.1		—		49.0
Substandard	30.8		5.4		12.8		5.5		1.6		3.4		35.2		1.5		96.2
Doubtful	—		1.6		1.1		0.5		—		—		—		—		3.2
Total	473.5		373.9		392.9		324.2		173.7		259.2		821.6		10.4		2,829.4

Agricultural:
Pass	109.6		34.1		39.4		16.6		13.5		5.8		379.4		1.1		599.5
Special mention	4.1		1.4		0.9		0.2		0.9		0.1		5.1		—		12.7
Substandard	4.1		25.9		0.1		—		0.5		—		25.9		0.3		56.8
Doubtful	18.9		—		—		—		—		—		—		—		18.9
Total	$	136.7	$	61.4	$	40.4	$	16.8	$	14.9	$	5.9	$	410.4	$	1.4	$	687.9

Table of Contents

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES

NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

(Dollars in millions, except share and per share data)

The Company evaluates the credit quality, loan performance, and the allowance for credit losses of its residential and consumer loan portfolios based primarily on the aging status of the loan and borrower payment activity. Accordingly, loans on non-accrual status and loans past due 90 days or more and still accruing interest are considered nonperforming for purposes of credit quality evaluation. The following tables present the recorded investment of these loan portfolios based on the credit risk profile of loans that are performing and loans that are nonperforming as of the periods indicated:


	September 30, 2025
	Term Loans Amortized Cost Basis by Origination Year
	2025		2024		2023		2022		2021		Prior		Revolving Loans Amortized Cost Basis		Revolving Loans Converted To Term		Total
Residential:
Performing	$	25.3	$	34.0	$	74.9	$	399.1	$	459.5	$	615.9	$	503.0	$	8.2	$	2,119.9
Nonperforming	0.5		1.0		1.8		5.2		2.3		5.2		0.1		—		16.1
Total	25.8		35.0		76.7		404.3		461.8		621.1		503.1		8.2		2,136.0

Consumer indirect:
Performing	31.1		192.6		87.5		116.5		46.2		61.6		—		—		535.5
Nonperforming	0.3		1.1		1.1		0.9		0.6		0.8		—		—		4.8
Total	31.4		193.7		88.6		117.4		46.8		62.4		—		—		540.3

Consumer direct and advance lines:
Performing	40.2		30.1		16.0		11.7		6.2		6.1		23.2		0.2		133.7
Nonperforming	0.2		0.2		0.1		0.1		—		—		—		—		0.6
Total	$	40.4	$	30.3	$	16.1	$	11.8	$	6.2	$	6.1	$	23.2	$	0.2	$	134.3


	December 31, 2024
	Term Loans Amortized Cost Basis by Origination Year
	2024		2023		2022		2021		2020		Prior		Revolving Loans Amortized Cost Basis		Revolving Loans Converted To Term		Total
Residential:
Performing	$	22.6	$	73.8	$	409.1	$	487.3	$	440.2	$	252.5	$	477.8	$	12.5	$	2,175.8
Nonperforming	1.3		1.5		4.9		2.1		1.1		4.9		—		—		15.8
Total	23.9		75.3		414.0		489.4		441.3		257.4		477.8		12.5		2,191.6

Consumer indirect:
Performing	266.8		127.2		167.5		68.9		44.4		45.6		—		—		720.4
Nonperforming	0.9		1.1		1.1		0.6		0.4		0.5		—		—		4.6
Total	267.7		128.3		168.6		69.5		44.8		46.1		—		—		725.0

Consumer direct and advance lines:
Performing	46.5		25.4		18.5		10.0		4.2		5.2		23.2		0.1		133.1
Nonperforming	0.4		0.1		0.2		0.1		—		0.1		—		—		0.9
Total	46.9		25.5		18.7		10.1		4.2		5.3		23.2		0.1		134.0

Consumer credit card:
Performing	—		—		—		—		—		—		76.6		—		76.6
Nonperforming	—		—		—		—&n

FIRST INTERSTATE BANCSYSTEM INC 10-Q