Not investment advice. Educational reading. See Disclaimer.
L.15 · BEGINNER · 3 MIN
How a Modern Bank Run Unfolds
Bank runs feel like a 20th-century phenomenon — black-and-white photographs of depositors queuing outside shuttered branches. The 2023 collapses of Silicon Valley Bank and Signature Bank were the modern version: same fundamental dynamic, transformed speed and venue. Understanding what changed matters for any investor holding bank stocks, bank bonds, or even uninsured deposits.
A bank run is a coordination failure, not a fundamental judgment. Even a healthy bank with adequate capital can fail if enough depositors withdraw at once, because the bank holds most of its assets in longer-term loans and securities that cannot be liquidated at full value on short notice. The 2023 events showed that this fragility persists despite a century of regulatory scaffolding.
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Element
Pre-2010 era
2023-era
Coordination venue
Physical branch lines, telephone trees
Twitter, Slack, WhatsApp groups, news aggregators
Withdrawal mechanism
Branch counter, wire request in-person
Mobile app wire transfer in seconds
Run duration
Days to weeks to develop and accelerate
Hours to a single business day
Depositor concentration
Diversified across retail and small business
Sometimes highly concentrated (VCs, crypto firms)
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FDIC insurance covers $250,000 per depositor per ownership category. Anything above that is 'uninsured' and historically has been at risk in a failure. In 2023 the FDIC and Treasury invoked the systemic-risk exception to backstop uninsured deposits at SVB and Signature — but that intervention was a discretionary policy choice, not a guarantee that depositors should expect in future failures.
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What an investor should learn from 2023, not how to predict the next collapse. Equity-holders at SVB and Signature received approximately zero. Bondholders took meaningful losses. The lessons are structural: when evaluating any bank you hold or might buy, examine deposit concentration (one industry? one geography? a few large customers?), the share of uninsured deposits, the size of unrealized losses on held-to-maturity securities, and the bank's disclosed liquidity coverage. A bank with diverse insured deposits, modest HTM losses, and ample liquidity is a much different animal than one with concentrated uninsured deposits and underwater HTM securities.
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Modern bank runs cannot be predicted from headlines because by the time the headline lands the run is already happening. The defensible posture is portfolio-level: do not concentrate large deposits at a single bank above the FDIC insurance limit, and when investing in bank equity, prefer institutions with structurally diversified and predominantly insured deposit bases over those with concentrated wholesale or uninsured funding.
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For one bank you currently hold or are considering, find the latest 10-K or 10-Q and look up: (1) percentage of deposits that are insured (FDIC-covered), (2) the largest customer concentration disclosure, and (3) unrealized losses on held-to-maturity securities relative to tangible common equity. Banks where uninsured deposits exceed 50 percent of total deposits, where HTM unrealized losses approach a quarter of equity, or where customer concentration is high warrant a closer second look before adding more.
§ 07
You hold shares of a regional bank whose latest 10-K shows 75 percent of deposits are insured, no single industry represents more than 15 percent of the deposit base, and unrealized HTM losses equal about 5 percent of tangible common equity. Compared to the 2023 failures, how is this bank positioned?
Five questions · AI feedback
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Sit with the ideas.
In March 2023 a large US regional bank suffered roughly $42 billion of attempted deposit withdrawals in a single business day — about a quarter of its total deposit base in a few hours. A prior-era textbook describes bank runs as multi-day queues of depositors lining up at branches. How did the 2023 dynamic differ, and what does the difference imply for any bank an investor owns today?
