When banks can dilute old debts, being connected and indebted makes the system safer.

Banks lend money to each other. When some banks suddenly need cash, the whole system can crash. The researchers created a model of this banking network to see what happens when bank debt is dilutable, meaning old lenders lose priority if the bank takes on new debt. In this setup, struggling banks can pledge their loans to other banks as collateral to borrow fresh, higher-priority cash. This process automatically spreads out the losses, working like a backdoor rescue without needing special government rules or renegotiation. Surprising as it sounds, more connections and more debt make this network more stable. While a specific shape called an exponential network shares cash best, banks naturally form different core-periphery structures that leave them under-insured.

Why it matters

Financial crises spread through banks that owe each other money. This model shows that letting banks issue new debt that waters down old claims can absorb shocks automatically, without regulators stepping in. That flips the usual worry: more interconnections and more debt can be stabilizing, not destabilizing. It also helps explain why real banking networks look the way they do—and why they may be under-prepared for the next crisis.

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