Form 11-K APARTMENT INVESTMENT & For: Dec 31

Note 1 — Description of the Plan

The following description of the Apartment Investment and Management Company Retirement Plan (the “Plan”) provides only general information. Participants should refer to the Plan document and Summary Plan Description for a more complete description of the Plan’s provisions.

General

On December 15, 2020, Apartment Investment and Management Company (“Aimco”) completed the separation of its businesses (the “Separation”), creating two, separate and distinct, publicly traded companies, Aimco and Apartment Income REIT Corp. (“AIR”). Concurrent with the Separation, the AIR 401(k) Retirement Plan (“AIR Plan”) was amended effective December 15, 2020. Aimco and its subsidiaries became participating employers in the AIR Plan and the AIR Plan became a multiple employer plan sponsored by AIR. There were no changes in benefits as a result of that amendment. The portion of the AIR Plan that covered Aimco employees was spun off and established as the Plan, effective January 1, 2023.

The Plan is a defined contribution plan subject to the Employee Retirement Income Security Act of 1974, as amended (“ERISA”). The Plan covers active regular employees in groups designated by Aimco, the Plan Sponsor, as eligible to participate in accordance with the Plan documents. Generally, an employee can participate in the Plan at age 18 or older, regardless of time of service. Fidelity Management Trust Company (“Fidelity”) serves as the Plan’s trustee and provides certain administrative services to the Plan.

Contributions

Each year, eligible participants may contribute up to 50% of their eligible compensation, or $23,500 for 2025, whichever is less. Participants who have attained age 50 before the end of the Plan year are eligible to make additional catch-up contributions up to $7,500 for 2025. Participants may also contribute amounts representing distributions from other qualified defined benefit, defined contribution plans and individual retirement accounts (rollovers).

Aimco has adopted the safe harbor design under Section 401(k)(12) of the Internal Revenue Code (“IRC”). The Plan provides for mandatory safe harbor contributions on behalf of each participant in the amount equal to 100% of the first 3% of the participant’s eligible compensation that is deferred, plus 50% of the next 2% of the participant's eligible compensation that is deferred, for a maximum total employer match of 4%. Aimco may also make a discretionary matching and discretionary nonelective contribution to all eligible participants; however, no discretionary contributions were made during the year ended December 31, 2025. All contributions are subject to certain limitations of the IRC.

Participants may direct their contributions, Aimco’s safe harbor contributions, and Aimco’s discretionary employer contributions, if any, into a variety of investment choices, which are more fully described in the Plan document and related agreements.

Participant Accounts

Each participant’s account is credited with the participant’s contributions, Aimco matching and discretionary contributions, and allocations of Plan earnings, and is charged with an allocation of administrative expenses. Plan earnings are allocated based on the participant’s share of net earnings or losses of their respective elected investment options. Allocations of administrative expenses are a fixed dollar amount per participant or per transaction type. The benefit to which a participant is entitled is their vested account balance at the time of distribution.

Vesting

Participants are immediately vested in their elective contributions, the safe harbor matching contributions, plus actual earnings and losses thereon. Discretionary nonelective and discretionary matching contributions and related earnings are fully vested after three years of service. Certain amounts that merged into the Plan retain their original vesting schedules.

Notes Receivable from Participants

Participants may borrow from their fund accounts a minimum of $1,000, up to a maximum equal to the lesser of the following amounts, reduced by the participant's highest aggregate loan balance during the 12 months preceding the loan:

Note 2 — Summary of Significant Accounting Policies

Note 3 —Fair Value Measurements and Investments

Fair value measurements enable the reader of the financial statements to assess the inputs used to develop those measurements by establishing a hierarchy for ranking the quality and reliability of the information used to determine fair values. In accordance with GAAP, the Plan classifies and discloses assets carried at fair value in one of the following three categories.

Level 1: Inputs are unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date.

Level 2: Inputs are observable inputs other than quoted (Level 1) prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The asset’s fair value measurements level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Classification within the fair value hierarchy table is based on the lowest level of any input that is significant to the fair value measurement. Valuation techniques used need to maximize the use of observable inputs and minimize the use of unobservable inputs.

Note 4 — Risks and Uncertainties

The Plan invests in various investment securities. Investment securities are exposed to various risks such as interest rate, market, liquidity, and credit risks. Due to the level of risk associated with certain investment securities, it is at least reasonably possible that changes in the fair value of certain investment securities will occur in the near term and that such changes could materially affect participants’ account balances and the amounts reported in the Statements of Net Assets Available for Benefits.

Note 5 — Income Tax Status

The underlying volume submitter plan has received an opinion letter from the Internal Revenue Service (“IRS”) dated June 30, 2020, stating that the form of the plan is qualified under Section 401 of the IRC and, therefore, the related trust is tax-exempt. Aimco has determined that it is eligible to, and has chosen to, rely on the current IRS volume submitter opinion letter. Once qualified, the Plan is required to operate in conformity with the IRC to maintain its qualified status. Although the Plan document has been amended since receiving the opinion letter, Aimco believes the Plan is being operated in compliance with the applicable requirements of the IRC and, therefore, believes the Plan is qualified and is tax-exempt.

GAAP requires Plan management to evaluate tax positions taken by the Plan and recognize a tax liability if the Plan has taken an uncertain position that more likely than not would not be sustained upon examination by the IRS. Plan management has analyzed the tax positions taken by the Plan and has concluded that there are no uncertain positions taken or expected to be taken as of December 31, 2025 and 2024. The Plan is subject to routine audits by taxing jurisdictions; however, there are currently no audits for any tax periods in progress.

Note 6 — Plan Termination

Subsequent to year end, on February 6, 2026, the stockholders of Aimco adopted a plan of sale and liquidation (the “Plan of Sale and Liquidation”), which contemplates the sale or disposition of all Aimco assets. In conjunction with the Plan of Sale and Liquidation, on April 30, 2026, Aimco's board of directors adopted a resolution to terminate the Plan effective July 31, 2026. Upon termination of the Plan, each participant will become fully vested and will receive a total distribution of the participant's account. The Plan's termination will cease employee and employer contributions into the Plan and cease new participant notes receivable from the Plan.

Note 7 — Related Party and Party-In-Interest Transactions

Transactions with a party-in-interest of the Plan, such as a sponsor, administrator, trustee, or participant, are considered either exempt or non-exempt from the prohibited transactions rules under ERISA. Non-exempt transactions are subject to penalty taxes.

Note 8 — Reconciliation from Financial Statements to Form 5500

The differences between the amounts presented on the Statements of Net Assets Available for Plan Benefits and Statement of Changes in Net Assets Available for Plan Benefits and the related Form 5500 are attributable to the value adjustment for the investments in the Fidelity MIP Fund, and contributions receivable in the current period.

The following is a reconciliation of net assets available for benefits per the financial statements at December 31, 2025 and December 31, 2024, to net assets per the Form 5500:

The following is a reconciliation of the net increase in net assets available for benefits per the financial statements at December 31, 2025, to net income per the Form 5500:

Note 9 — Subsequent Events

The Plan has evaluated all subsequent events through June 23, 2026, which represents when the financial statements were issued, to ensure that the Plan’s financial statements include appropriate disclosure of events both recognized in the financial statements as of December 31, 2025, and events which occurred subsequent to December 31, 2025, but were not recognized in the financial statements. Aimco is not aware of any subsequent events which would require recognition in the financial statements.

Refer to Note 6 – Plan Termination for subsequent event disclosure related to the anticipated termination of the Plan in connection with Aimco’s Plan of Sale and Liquidation.

Apartment Investment and Management Company Retirement Plan