Diamond Hill Investment Group is a pure-play active investment management firm that operates through its wholly-owned subsidiary, Diamond Hill Capital Management. Diamond Hill manages roughly $29.4B in AUM for institutional clients — pension plans, endowments, foundations, and other large pools of capital — using valuation-disciplined, fundamental, long-term strategies across U.S. equity, fixed income, alternatives, and international equity. U.S. equity is the largest segment at ~61% of AUM, anchored by the Large Cap strategy, though this segment has faced outflows in recent years. Fixed income has been the fastest-growing area, expanding from ~$3.7B in 2023 to ~$8.9B in 2025. Diamond Hill distributes its strategies through mutual funds, SMAs, ETFs, CITs, and sub-advised vehicles, with proprietary funds generating roughly 70% of total revenue. Revenue is almost entirely advisory and fund administration fees tied directly to AUM levels and mix. A shift in AUM toward lower-fee fixed income strategies compresses the blended fee rate even when total AUM holds steady. Diamond Hill runs a lean operation of ~120 employees, so revenue changes flow heavily to the bottom line. The firm intentionally caps strategy sizes to protect investment performance, which limits AUM growth. In December 2025, Diamond Hill entered into a merger agreement with First Eagle Investment Management, under which First Eagle will acquire Diamond Hill for $175.00 per share in cash. The deal is expected to close in Q2 2026, after which Diamond Hill would operate as a wholly-owned subsidiary of First Eagle, a privately-owned active manager with ~$181B in AUM.