---
schema_version: "secwatch.filing_event.v1"
accession: "0000860413-23-000190"
form_type: "8-K"
ticker: "FIBK"
cik: "0000860413"
company_name: "FIRST INTERSTATE BANCSYSTEM INC"
filed_at: "2023-11-30T23:59:59+00:00"
generated_at: "2026-06-07T20:09:54.480482+00:00"
event_type: "other_material"
sentiment: "neutral"
materiality_score: 0.5
calibrated_materiality_score: 0.5
confidence: "high"
source: SEC EDGAR
---

# First Interstate BancSystem dismisses RSM as auditor, appoints EY for FY2024

## Summary
- Audit Committee dismissed RSM US LLC on Nov 28, 2023; RSM completes 2023 audit.
- No disagreements or reportable events between Company and RSM during 2021-2023.
- RSM's 2021 and 2022 audit reports were unqualified with no adverse opinions.
- Ernst & Young LLP engaged as new independent auditor for fiscal year ending Dec 31, 2024.
- RSM furnished a letter to the SEC agreeing with the Company's disclosures (Exhibit 16.1).

## SEC filing metadata
- accession: 0000860413-23-000190
- form_type: 8-K
- ticker: FIBK
- cik: 0000860413
- company_name: FIRST INTERSTATE BANCSYSTEM INC
- filed_at: 2023-11-30T23:59:59+00:00
- event_type: other_material
- sentiment: neutral
- materiality_score: 0.5
- calibrated_materiality_score: 0.5
- confidence: high
- sec_items: 4.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/860413/000086041323000190/0000860413-23-000190-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/860413/000086041323000190/fibk-20231128.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000860413-23-000190
- JSON: https://secwatch.observer/filing/0000860413-23-000190.json
- Plain text: https://secwatch.observer/filing/0000860413-23-000190.txt

## Key facts
- Auditor Changes
  FIRST INTERSTATE BANCSYSTEM INC dismissed RSM US LLC as its auditor.
  - Action: dismissal
  - Auditor: RSM US LLC
  - Successor: Ernst & Young LLP
  source text: On November 28, 2023, the Audit Committee (the “Audit Committee”) of the Board of Directors of First Interstate BancSystem, Inc. (the “Company”) approved the dismissal of its current independent registered public accounting firm, RSM US LLC (“RSM”), in connection with its change to its new independent registered public accounting firm, Ernst & Young LLP (“EY”), for the Company’s fiscal year ending December 31, 2024, as further described below.
  evidence_url: https://www.sec.gov/Archives/edgar/data/860413/000086041323000190/0000860413-23-000190-index.htm
- Auditor Changes
  FIRST INTERSTATE BANCSYSTEM INC engaged Ernst & Young LLP as its auditor.
  - Action: engagement
  - Auditor: Ernst & Young LLP
  source text: On November 28, 2023, the Audit Committee approved the engagement of EY to be the Company’s independent registered public accounting firm to perform independent audit services for the Company beginning with its fiscal year ending December 31, 2024.
  evidence_url: https://www.sec.gov/Archives/edgar/data/860413/000086041323000190/0000860413-23-000190-index.htm

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.