I show that investor composition affects bond price dynamics and capital allocation during crises. Using large-scale holdings data and within-firm ownership variation across near-identical bonds, I causally identify bond returns’ investor composition elasticities. Corporate bonds held predominantly by insurers rather than mutual funds suffer milder losses in downturns: increasing insurer holdings by half a bond’s size causes 20% shallower drawdowns. A shift-share instrument isolates variation from large insurers’ idiosyncratic primary-market allocations. Differences in intermediaries’ liability structures drive these results, which hold across countries. During crises, firms with more stable bondholders maintain higher borrowing at lower cost and invest more.