This paper investigates the capital structure implications of defined-benefit (DB) pension obligations, which represent a form of 'hidden leverage' that is economically equivalent to unsecured long-term debt but is often excluded from standard leverage measures. Using hand-collected pension data for 2,870 firms with DB plans across 16 countries over 2005-2024, we construct an 'augmented leverage' measure that adds the present value of net pension obligations to traditional debt. Our findings reveal that: (1) pension-augmented leverage is, on average, 7.4 percentage points higher than traditional book leverage; (2) credit markets price pension leverage as approximately 78% equivalent to financial debt, confirming that pension obligations represent genuine leverage; (3) firms with large pension deficits substitute financial debt with pension debt, reflecting a 'crowding out' effect; (4) pension risk management significantly affects both pension-augmented and financial leverage, where firms completing pension risk transfers increase financial leverage by 3.4 pp within two years as eliminating pension risk frees debt capacity; (5) the 2022 UK gilt crisis provides a natural experiment demonstrating the systemic risk of pension-capital structure interconnections.