Organization and Basis of Presentation (Policies)	3 Months Ended
Mar. 31, 2026
Accounting Policies [Abstract]
Nature of Operations	The consolidated financial statements include the accounts of FirstSun Capital Bancorp (“FirstSun” or “Parent Company”) and its wholly-owned subsidiaries, Sunflower Bank, N.A. (the “Bank”), Sunflower Wealth Advisors LLC, and FEIF Capital Partners, LLC, and have been prepared using U.S. generally accepted accounting principles (“GAAP”) and prevailing practices in the banking industry. All significant intercompany balances and transactions have been eliminated. These entities are collectively referred to as “our”, “us”, “we”, or “the Company”.
Basis of Presentation	The consolidated financial statements in this Quarterly Report on Form 10-Q have been prepared in accordance with GAAP for interim financial information, but do not include all of the information and footnotes required by GAAP for a full year presentation and certain disclosures have been condensed or omitted in accordance with rules and regulations of the SEC. These interim financial statements are unaudited, and include, in our opinion, all adjustments necessary for a fair statement of the results for the periods indicated, which are not necessarily indicative of results which may be expected for the full year. These unaudited consolidated financial statements and notes should be read in conjunction with FirstSun’s audited consolidated financial statements and footnotes thereto for the year ended December 31, 2025, included in our 2025 Annual Report.
Use of Estimates	The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions based on available information. These estimates and assumptions affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. These estimates are based on historical experience and on various assumptions about the future that are believed to be reasonable based on all available information. Our reported financial position or results of operations may be materially different under changed conditions or when using different estimates and assumptions, particularly with respect to critical accounting policies. In the event that estimates or assumptions prove to differ from actual results, adjustments are made in subsequent periods to reflect more current information.
Reclassifications	Some items in the prior year financial statements were reclassified to conform to the current presentation. Previously, deposit amounts related to certain NOW accounts with limited monthly transaction activity were able to be reclassified to money market accounts to reduce reserve requirements at the Federal Reserve. As there is no longer any impact to reserve requirements across different deposit products, we have discontinued this product reclassification practice and have revised the presentation of those deposits to conform to the current presentation for periods prior to March 31, 2026. Reclassifications had no effect on prior years net income or stockholders’ equity.
Accounting Pronouncements Recently Adopted and Recent Accounting Pronouncements Not Yet Adopted	As an “emerging growth company” under Section 107 of the JOBS Act, we can take advantage of the extended transition period provided in Section 7(a)(2)(B) of the Securities Act for complying with new or revised accounting standards. Therefore, we can delay the adoption of certain accounting standards until those standards would otherwise apply to non-public business entities. We intend to take advantage of the benefits of this extended transition period for an “emerging growth company” for as long as it is available to us. For standards that we have delayed adoption, we may lack comparability to other companies who have adopted such standards. ASU No. 2025-05, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets.” ASU 2025-05 provides all entities, when developing reasonable and supportable forecasts as part of estimating expected credit losses on current accounts receivable and/or current contract assets arising from transactions under ASC Topic 606 - Revenue from Contracts with Customers, a practical expedient whereby entities can assume that current conditions as of the balance sheet date do not change for the remaining life of the asset. ASU 2025-05 became effective for us in 2026 and did not have a significant impact on our financial statements. Recent Accounting Pronouncements Not Yet Adopted - ASU No. 2024-03, “Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses.” ASU 2024-03 requires disaggregated disclosure of income statement expenses for public business entities. ASU 2024-03 requires new financial statement disclosures in tabular format, disaggregating information about prescribed categories underlying any relevant income statement expense caption. The prescribed categories include, among other things, employee compensation, depreciation, and intangible asset amortization. Additionally, entities must disclose the total amount of selling expenses and, in annual reporting periods, an entity’s definition of selling expenses. ASU 2024-03 will be effective for us, on a prospective basis, for annual periods beginning in 2027, and interim periods within fiscal years beginning in 2028, though early adoption and retrospective application is permitted. ASU 2024-03 is not expected to have a significant impact on our financial statements. ASU No. 2025-06, “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software.” ASU 2025-06 simplifies and modernizes the accounting for internal-use software by removing prescriptive project stage guidance and introducing a new capitalization threshold. Under the revised standard, software development costs are capitalized when management authorizes and commits funding for the project and it is probable the software will be completed and used as intended. ASU 2025-06 will be effective in 2028 and is not expected to have a significant impact on our financial statements. ASU 2025‑08, “Financial Instruments - Credit Losses (Topic 326): Purchased Loans.” ASU 2025-08 expands the scope of the “gross‑up” method, formerly applicable only to purchased credit‑deteriorated (“PCD”) assets, to include acquired non‑PCD loans that meet certain criteria, now referred to as “purchased seasoned loans” (PSLs). Under this model, an allowance for expected credit losses is recognized at acquisition, offsetting the loan’s amortized cost basis, thereby eliminating the day-one credit‑loss expense previously required for non‑PCD assets. PSLs are defined as non‑PCD loans acquired either (i) through a business combination, or (ii) purchased more than 90 days after origination when the acquirer was not involved in origination. ASU 2025-08 will be effective for us, on a prospective basis for loans acquired on or after the adoption date, for interim and annual reporting periods beginning in 2027, though early adoption is permitted. We plan to early adopt on April 1, 2026 in conjunction with our acquisition of First Foundation Inc. We are not currently able to estimate the impact adoption will have on our financial statements, as our purchase accounting estimates are not yet complete. ASU 2025‑09, “Derivatives and Hedging (Topic 815): Hedge Accounting Improvements.” ASU 2025-09 amends ASC 815 to align hedge accounting more closely with an entity’s economic risk management practices. Key amendments include (i) to allow designating a variable price component of a nonfinancial forecasted purchase or sale as the hedged risk, (ii) to allow grouping individual forecasted transactions with similar (not identical) risk exposures, (iii) a new model for hedging forecasted interest on variable-rate debt, enabling changes in index or tenor without dedesignation, subject to simplifying assumptions, and (iv) additional clarifications related to hedge accounting of nonfinancial components, net written options, and dual-hedge strategies. ASU 2025-09 will be effective for us beginning in 2027, though early adoption is permitted. ASU 2025-09 is not expected to have a significant impact on our financial statements. ASU 2025‑11, “Interim Reporting (Topic 270): Narrow‑Scope Improvements.” ASU 2025-11 clarifies and enhances guidance under ASC 270 on interim financial reporting by (i) clarifying the scope of ASC 270 such that it now explicitly applies only to entities that issue complete interim financial statements and related notes under U.S. GAAP, (ii) establishing clear guidance on the form of interim statements and notes, incorporating a comprehensive list of required interim disclosures drawn from across the ASC, and (iii) introducing a requirement to disclose material events and changes occurring after the end of the last annual period that could impact interim results. ASU 2025-11 will be effective for us for interim periods beginning in 2028, though early adoption is permitted. ASU 2025-11 is not expected to have a significant impact on our financial statements.

Organization and Basis of Presentation (Policies)

3 Months Ended

Mar. 31, 2026

The consolidated financial statements include the accounts of FirstSun Capital Bancorp (“FirstSun” or “Parent Company”) and its wholly-owned subsidiaries, Sunflower Bank, N.A. (the “Bank”), Sunflower Wealth Advisors LLC, and FEIF Capital Partners, LLC, and have been prepared using U.S. generally accepted accounting principles (“GAAP”) and prevailing practices in the banking industry. All significant intercompany balances and transactions have been eliminated. These entities are collectively referred to as “our”, “us”, “we”, or “the Company”.

Basis of Presentation

The consolidated financial statements in this Quarterly Report on Form 10-Q have been prepared in accordance with GAAP for interim financial information, but do not include all of the information and footnotes required by GAAP for a full year presentation and certain disclosures have been condensed or omitted in accordance with rules and regulations of the SEC. These interim financial statements are unaudited, and include, in our opinion, all adjustments necessary for a fair statement of the results for the periods indicated, which are not necessarily indicative of results which may be expected for the full year. These unaudited consolidated financial statements and notes should be read in conjunction with FirstSun’s audited consolidated financial statements and footnotes thereto for the year ended December 31, 2025, included in our 2025 Annual Report.

Use of Estimates

The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions based on available information. These estimates and assumptions affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

These estimates are based on historical experience and on various assumptions about the future that are believed to be reasonable based on all available information. Our reported financial position or results of operations may be materially different under changed conditions or when using different estimates and assumptions, particularly with respect to critical accounting policies. In the event that estimates or assumptions prove to differ from actual results, adjustments are made in subsequent periods to reflect more current information.

Reclassifications

Some items in the prior year financial statements were reclassified to conform to the current presentation. Previously, deposit amounts related to certain NOW accounts with limited monthly transaction activity were able to be reclassified to money market accounts to reduce reserve requirements at the Federal Reserve. As there is no longer any impact to reserve requirements across different deposit products, we have discontinued this product reclassification practice and have revised the presentation of those deposits to conform to the current presentation for periods prior to March 31, 2026. Reclassifications had no effect on prior years net income or stockholders’ equity.

Accounting Pronouncements Recently Adopted and Recent Accounting Pronouncements Not Yet Adopted

As an “emerging growth company” under Section 107 of the JOBS Act, we can take advantage of the extended transition period provided in Section 7(a)(2)(B) of the Securities Act for complying with new or revised accounting standards. Therefore, we can delay the adoption of certain accounting standards until those standards would otherwise apply to non-public business entities. We intend to take advantage of the benefits of this extended transition period for an “emerging growth company” for as long as it is available to us. For standards that we have delayed adoption, we may lack comparability to other companies who have adopted such standards.

ASU No. 2025-05, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets.” ASU 2025-05 provides all entities, when developing reasonable and supportable forecasts as part of estimating expected credit losses on current accounts receivable and/or current contract assets arising from transactions under ASC Topic 606 - Revenue from Contracts with Customers, a practical expedient whereby entities can assume that current conditions as of the balance sheet date do not change for the remaining life of the asset. ASU 2025-05 became effective for us in 2026 and did not have a significant impact on our financial statements.

Recent Accounting Pronouncements Not Yet Adopted - ASU No. 2024-03, “Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses.” ASU 2024-03 requires disaggregated disclosure of income statement expenses for public business entities. ASU 2024-03 requires new financial statement disclosures in tabular format, disaggregating information about prescribed categories underlying any relevant income statement expense caption. The prescribed categories include, among other things, employee compensation, depreciation, and intangible asset amortization. Additionally, entities must disclose the total amount of selling expenses and, in annual reporting periods, an entity’s definition of selling expenses. ASU 2024-03 will be effective for us, on a prospective basis, for annual periods beginning in 2027, and interim periods within fiscal years beginning in 2028, though early adoption and retrospective application is permitted. ASU 2024-03 is not expected to have a significant impact on our financial statements.

ASU No. 2025-06, “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software.” ASU 2025-06 simplifies and modernizes the accounting for internal-use software by removing prescriptive project stage guidance and introducing a new capitalization threshold. Under the revised standard, software development costs are capitalized when management authorizes and commits funding for the project and it is probable the software will be completed and used as intended. ASU 2025-06 will be effective in 2028 and is not expected to have a significant impact on our financial statements.

ASU 2025‑08, “Financial Instruments - Credit Losses (Topic 326): Purchased Loans.” ASU 2025-08 expands the scope of the “gross‑up” method, formerly applicable only to purchased credit‑deteriorated (“PCD”) assets, to include acquired non‑PCD loans that meet certain criteria, now referred to as “purchased seasoned loans” (PSLs). Under this model, an allowance for expected credit losses is recognized at acquisition, offsetting the loan’s amortized cost basis, thereby eliminating the day-one credit‑loss expense previously required for non‑PCD assets. PSLs are defined as non‑PCD loans acquired either (i) through a business combination, or (ii) purchased more than 90 days after origination when the acquirer was not involved in origination. ASU 2025-08 will be effective for us, on a prospective basis for loans acquired on or after the adoption date, for interim and annual reporting periods beginning in 2027, though early adoption is permitted. We plan to early adopt on April 1, 2026 in conjunction with our acquisition of First Foundation Inc. We are not currently able to estimate the impact adoption will have on our financial statements, as our purchase accounting estimates are not yet complete.

ASU 2025‑09, “Derivatives and Hedging (Topic 815): Hedge Accounting Improvements.” ASU 2025-09 amends ASC 815 to align hedge accounting more closely with an entity’s economic risk management practices. Key amendments include (i) to allow designating a variable price component of a nonfinancial forecasted purchase or sale as the hedged risk, (ii) to allow grouping individual forecasted transactions with similar (not identical) risk exposures, (iii) a new model for hedging forecasted interest on variable-rate debt, enabling changes in index or tenor without dedesignation, subject to simplifying assumptions, and (iv) additional clarifications related to hedge accounting of nonfinancial components, net written options, and dual-hedge strategies. ASU 2025-09 will be effective for us beginning in 2027, though early adoption is permitted. ASU 2025-09 is not expected to have a significant impact on our financial statements.

ASU 2025‑11, “Interim Reporting (Topic 270): Narrow‑Scope Improvements.” ASU 2025-11 clarifies and enhances guidance under ASC 270 on interim financial reporting by (i) clarifying the scope of ASC 270 such that it now explicitly applies only to entities that issue complete interim financial statements and related notes under U.S. GAAP, (ii) establishing clear guidance on the form of interim statements and notes, incorporating a comprehensive list of required interim disclosures drawn from across the ASC, and (iii) introducing a requirement to disclose material events and changes occurring after the end of the last annual period that could impact interim results. ASU 2025-11 will be effective for us for interim periods beginning in 2028, though early adoption is permitted. ASU 2025-11 is not expected to have a significant impact on our financial statements.