A transaction in previously-issued partnership interests (LP secondary) or portfolio-company stakes (GP-led continuation vehicle, strip sale, tender offer). The secondary market has grown from a niche to $100-150 billion in annual volume, split roughly 50-50 between LP-led and GP-led transactions by 2025. LP interests typically trade at 3-30% discount to NAV depending on strategy, vintage, and market conditions (buyout: 3-8% in strong markets, 20-30%+ in stressed). Secondary buyers underwrite by re-valuing portfolio companies bottom-up and discounting projected cash flows at 15-25% target IRR.