This article explores the economic issues related to financial crises at insurance companies, using an example from the Great Depression, the National Surety Company. National Surety was a large and diverse American insurance company that experienced a major crisis in 1933 due to losses from its guarantees of mortgage-backed securities. I find that policyholders were able to stage a massive run on the company by demanding the return of their unearned premiums. A key dynamic of the crisis was that policyholders at an insurance company have a dual role as holders of liabilities and as providers of income. In addition, I establish that government officials believed National Surety to be systemically important, due to the size of its insurance business and because many of its counterparties were societal actors that these officials sought to protect. As a result, the New York State Insurance Commissioner used emergency powers to reorganize the company, with the goal of providing continuity to its business lines outside mortgage-backed security insurance.