Organization and Description of the Business	12 Months Ended
Dec. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of the Business	Organization and Description of the Business Acadian Asset Management Inc. (“Acadian”, “AAMI” or the “Company”), is a holding company that operates a systematic investment management business through its majority owned subsidiary, Acadian Asset Management LLC (“Acadian LLC”). Acadian LLC offers institutional investors across the globe access to a diversified array of systematic investment strategies designed to meet a range of risk and return objectives. Acadian LLC is a leading systematic investment manager of active equity products. Notable product lines and capabilities include Emerging Equity, Non-U.S. Equity, Global Equity, Small Cap Equity, Enhanced Equity, Equity Extensions, Systematic Credit, and Alternatives. Acadian LLC comprises the Company’s Quant & Solutions reportable segment: •Quant & Solutions—incorporates strategies that utilize advanced technology to collect and analyze data, aiming to identify mispriced assets and generate attractive risk-adjusted returns for investors; portfolios include Emerging Equity, Non-U.S. Equity, Global Equity, Small Cap Equity, Enhanced Equity, Equity Extensions, and Systematic Credit. Acadian LLC is organized as a limited liability company. Fees for services are largely asset-based and, as a result, revenues fluctuate based on the performance of financial markets and investors’ asset flows in and out of Acadian LLC’s products. The Company utilizes a profit-sharing model in structuring its compensation and ownership arrangements with Acadian LLC. Variable compensation is based on the firm’s profitability. The Company and Acadian LLC key employees share in profits after variable compensation according to their respective ownership interests. The profit-sharing model results in the alignment of the Company and Acadian LLC key employee economic interests, which is critical to the Company’s talent management strategy and long-term growth of the business. Prior to 2014, the Company was a wholly-owned subsidiary of Old Mutual plc (“OM plc”), an international long-term savings, protection, and investment group, listed on the London Stock Exchange. On October 15, 2014, the Company completed the initial public offering (the “Offering”) by OM plc pursuant to the Securities Act of 1933, as amended. As part of the Offering, the Company was authorized to issue up to 230 million shares of $0.001 par value per share common stock. As of December 31, 2025, Paulson & Co. Inc. (“Paulson”) and related parties thereof held approximately 21.8% of the common stock of the Company. In February 2025, the Company’s Board of Directors authorized an $80 million share repurchase program. For the year ended December 31, 2025, the Company repurchased 1,799,423 shares of common stock at an average price of $26.64 per share, or approximately $48.0 million in total, including commissions. In connection with these repurchases, a reduction to additional paid-in capital in the amount of $1.7 million was recorded until it was depleted, with the remaining $46.3 million of share repurchases recorded to retained earnings. For the year ended December 31, 2024, the Company repurchased 4,445,534 shares of common stock at an average price of $21.32 per share, or approximately $94.9 million in total, including commissions. In connection with these repurchases, a reduction to additional paid-in capital in the amount of $0.4 million was recorded until it was depleted, with the remaining $94.5 million of share repurchases recorded to retained earnings. For the year ended December 31, 2023, the Company repurchased 268,800 shares of common stock at an average price of $19.03 per share, or approximately $5.1 million in total, including commissions. In connection with these repurchases, a reduction to additional paid-in capital in the amount of $(0.3) million was recorded until it was depleted, with the remaining $4.8 million of repurchases recorded to retained earnings. All shares of common stock repurchased by the Company were retired.

Acadian Asset Management Inc. (“Acadian”, “AAMI” or the “Company”), is a holding company that operates a systematic investment management business through its majority owned subsidiary, Acadian Asset Management LLC (“Acadian LLC”). Acadian LLC offers institutional investors across the globe access to a diversified array of systematic investment strategies designed to meet a range of risk and return objectives. Acadian LLC is a leading systematic investment manager of active equity products. Notable product lines and capabilities include Emerging Equity, Non-U.S. Equity, Global Equity, Small Cap Equity, Enhanced Equity, Equity Extensions, Systematic Credit, and Alternatives. Acadian LLC comprises the Company’s Quant & Solutions reportable segment:

•Quant & Solutions—incorporates strategies that utilize advanced technology to collect and analyze data, aiming to identify mispriced assets and generate attractive risk-adjusted returns for investors; portfolios include Emerging Equity, Non-U.S. Equity, Global Equity, Small Cap Equity, Enhanced Equity, Equity Extensions, and Systematic Credit.

Acadian LLC is organized as a limited liability company. Fees for services are largely asset-based and, as a result, revenues fluctuate based on the performance of financial markets and investors’ asset flows in and out of Acadian LLC’s products. The Company utilizes a profit-sharing model in structuring its compensation and ownership arrangements with Acadian LLC. Variable compensation is based on the firm’s profitability. The Company and Acadian LLC key employees share in profits after variable compensation according to their respective ownership interests. The profit-sharing model results in the alignment of the Company and Acadian LLC key employee economic interests, which is critical to the Company’s talent management strategy and long-term growth of the business.

Prior to 2014, the Company was a wholly-owned subsidiary of Old Mutual plc (“OM plc”), an international long-term savings, protection, and investment group, listed on the London Stock Exchange. On October 15, 2014, the Company completed the initial public offering (the “Offering”) by OM plc pursuant to the Securities Act of 1933, as amended. As part of the Offering, the Company was authorized to issue up to 230 million shares of $0.001 par value per share common stock. As of December 31, 2025, Paulson & Co. Inc. (“Paulson”) and related parties thereof held approximately 21.8% of the common stock of the Company.

In February 2025, the Company’s Board of Directors authorized an $80 million share repurchase program. For the year ended December 31, 2025, the Company repurchased 1,799,423 shares of common stock at an average price of $26.64 per share, or approximately $48.0 million in total, including commissions. In connection with these repurchases, a reduction to additional paid-in capital in the amount of $1.7 million was recorded until it was depleted, with the remaining $46.3 million of share repurchases recorded to retained earnings.

For the year ended December 31, 2024, the Company repurchased 4,445,534 shares of common stock at an average price of $21.32 per share, or approximately $94.9 million in total, including commissions. In connection with these repurchases, a reduction to additional paid-in capital in the amount of $0.4 million was recorded until it was depleted, with the remaining $94.5 million of share repurchases recorded to retained earnings.

For the year ended December 31, 2023, the Company repurchased 268,800 shares of common stock at an average price of $19.03 per share, or approximately $5.1 million in total, including commissions. In connection with these repurchases, a reduction to additional paid-in capital in the amount of $(0.3) million was recorded until it was depleted, with the remaining $4.8 million of repurchases recorded to retained earnings.