The following table details investments by major investment category, other than investments in related parties, at June 30, 2025 and December 31, 2024 (in thousands):

Fair value measurement

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The hierarchy for inputs used in determining fair value maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Assets and liabilities recorded on our Consolidated Balance Sheets at fair value are categorized in the fair value hierarchy based on the observability of inputs to the valuation techniques as follows:

Level 1: Assets and liabilities whose values are based on unadjusted quoted prices for identical assets or liabilities in an active market that we can access.

Level 2: Assets and liabilities whose values are based on the following:

Level 3: Assets and liabilities whose values are based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. Unobservable inputs reflect our estimates of the assumptions that market participants would use in valuing the assets and liabilities.

On June 30, 2025, the Company completed a non-cash equity-for-equity exchange transaction acquiring a 39.1% equity interest (10.4% voting interest) in ACMAT Corporation. For further information, refer to Note 3, Significant Transactions. As of June 30, 2025, the Company's investment in ACMAT Corporation was carried at $12.5 million. The Company accounts for this investment under ASC 321, Investments – Equity Securities, and measures it at fair value on a recurring basis through net income. 

The Company did not record any re-valuation income or loss from this investment during the three- and six-month periods ended June 30, 2025. The Company determined fair value of its investment in ACMAT Corporation using Level 2 inputs. Specifically, the valuation was based on trades of the Company's common stock on the over-the-counter market on the Over-the-Counter Quotation Bureau, adjusted by management using a control premium assumption, a discount for marketability assumption and an internal valuation incorporating book value of the investee and peer company multiples. Level 2 inputs were used as ACMAT Corporation does not have an active trading market and its public float is limited (4% of shares outstanding). 

The Company's fixed-income securities portfolio was classified as held-to-maturity and reported at amortized cost as of December 31, 2024. The Company performed ongoing impairment evaluations, and did not record any current expected credit losses in previous periods as U.S. government and agency securities were assumed to have no risk of non-payment. The disclosed fair value of our fixed-income securities was calculated by a third-party pricing service. Valuation service providers typically obtain data about market transactions and other key valuation model inputs from multiple sources and, through the use of proprietary models, produce valuation information in the form of a single fair value for individual fixed-income and other securities for which a fair value has been requested. The inputs used by the valuation service providers included, but were not limited to, market prices from recently completed transactions and transactions of comparable securities, interest rate yield curves, credit spreads, liquidity spreads, currency rates and other information, as applicable. Credit and liquidity spreads are typically implied from completed transactions and transactions of comparable securities. Valuation service providers also use proprietary discounted cash flow models that are widely accepted in the financial services industry and similar to those used by other market participants to value the same financial information. The valuation models take into account, among other things, market observable information as of the measurement date, as described above, as well as the specific attributes of the security being valued, including its term, interest rate, credit rating, industry sector and, where applicable, collateral quality and other issue or issuer specific information. Executing valuation models effectively requires seasoned professional judgment and experience. The Company's fixed-income securities as of December 31, 2024 were classified as Level 2 in the fair value hierarchy. 

The Company has elected the practical expedient for fair value for its investment in limited partnership which is estimated based on our share of the net asset value (“NAV”) of the limited partnership, as provided by the independent fund administrator. The Company’s share of the NAV represents the Company’s proportionate interest in the members’ equity of the limited partnership.

The following tables present fair value, by valuation hierarchy, and carrying value of the financial instruments measured at fair value or for which fair value is disclosed as of June 30, 2025 and December 31, 2024 (in thousands):

Net investment income

Net investment income for the three and six months ended June 30, 2025 and 2024 is detailed below (in thousands):