What causes stablecoin depegging cascades, and how does contagion spread between stablecoins?

30 September 2026

A stablecoin depegging cascade occurs when one stablecoin loses its peg to a target asset (usually the US dollar), and that failure triggers a loss of confidence or direct financial losses in other stablecoins, causing them to also depeg. Contagion spreads through shared collateral, arbitrage mechanisms, liquidity pools, and investor psychology. The result can be a rapid, self-reinforcing collapse across multiple stablecoins in a matter of hours.

The trigger: how a single depeg begins

A depeg starts when the market price of a stablecoin falls significantly below its target - typically 1 cent or more below $1. This can happen due to:

• A sudden large sell order that overwhelms available buy-side liquidity.
• A run on redemptions if holders doubt the backing assets are sufficient or accessible.
• A failure in the mint-and-redeem arbitrage loop that normally restores the peg.
• A smart contract exploit or oracle manipulation that drains reserves or mints unbacked tokens.

Once the price breaks below a psychologically important threshold (often $0.98 or $0.99), panic selling can accelerate the drop.

The mechanics of contagion

Contagion spreads through several distinct channels. They often operate simultaneously.

1. Shared Collateral

Many stablecoins hold similar reserve assets: US Treasury bills, commercial paper, or other stablecoins themselves. When one stablecoin depegs and faces mass redemptions, it may need to liquidate its collateral quickly. If that collateral includes another stablecoin, the selling pressure depegs that second coin. For example, if a large algorithmic stablecoin holds significant amounts of USDC as backing, and USDC itself comes under pressure, the selling of USDC by the first coin's protocol can accelerate USDC's depeg.

2. cross-protocol liquidity pools

Decentralized exchanges and lending protocols pool stablecoins together. A liquidity pool containing USDT, USDC, DAI, and a depegging stablecoin will see its ratio shift. Traders can exploit the price difference by swapping the depegged coin for the still-pegged ones, draining the pool of the healthier stablecoins. As the pool's composition changes, the remaining stablecoins face increased selling pressure.

3. Arbitrage Failure

Normally, arbitrageurs restore a depegged stablecoin's price by buying it cheap and redeeming it at face value with the issuer. But if the issuer's redemption process is slow, frozen, or perceived as risky, arbitrageurs may stop acting. Worse, if the depegged coin is used as collateral in lending protocols, liquidations can cascade. Borrowers who used the depegged coin as collateral face margin calls, forcing them to sell other assets - including other stablecoins - to cover their positions.

4. Psychological Contagion

Fear spreads faster than funds. When one stablecoin breaks its peg, holders of other stablecoins worry about the safety of their own holdings. This can trigger a "flight to safety" where users redeem multiple stablecoins simultaneously for fiat or for bitcoin and ether. Even well-backed stablecoins can briefly depeg if too many redemption requests hit the issuer at once, especially during off-hours or weekends when bank settlement is unavailable.

Real-World Patterns

Historical depegging events show recurring patterns:

• The May 2022 TerraUSD collapse began when UST lost its peg, and its sister token LUNA hyperinflated. The resulting sell-off in LUNA spread to other stablecoins because many protocols used LUNA as collateral. It also triggered a broad crypto market sell-off that pressured USDT, which briefly traded at $0.95.

• The March 2023 USDC depeg occurred when Circle disclosed that $3.3 billion of its reserves were held at Silicon Valley Bank during a bank run. USDC fell to $0.87. This immediately affected DAI, which held significant USDC as backing, causing DAI to drop to $0.88. USDT briefly traded above $1.00 as traders rotated into it, but then also faced selling pressure as the broader market panicked.

In both cases, the contagion was contained because the underlying collateral for USDC and USDT was ultimately recoverable, and the issuers had redemption mechanisms that worked - albeit with delays.

How Contagion Stops

Contagion ends when one or more of the following occur:

• The original depegged stablecoin restores its peg through arbitrage or issuer intervention.
• A large buyer or market maker steps in to support prices.
• The issuer of a second stablecoin provides transparent proof that its reserves are intact and accessible.
• Centralized exchanges halt trading or withdrawals for the affected coins, buying time.
• Bank markets reopen, allowing fiat redemptions to resume.

Key vulnerabilities that amplify cascades

Certain conditions make cascades more likely and more severe:

• Overlapping reserve compositions where multiple stablecoins hold the same risky assets.
• High leverage in lending protocols that use stablecoins as collateral.
• Slow or gated redemption processes that prevent arbitrage from working quickly.
• Low liquidity in the stablecoin's trading pairs, especially during off-hours.
• Lack of real-time proof of reserves that leaves holders uncertain about backing.

Practical Implications

For users, the risk of contagion means that holding a single stablecoin is not necessarily safer than holding several. During a cascade, all stablecoins in the same ecosystem can suffer. Diversifying across stablecoins with different reserve types - fiat-backed, crypto-backed, and commodity-backed - can reduce exposure, but only if those reserves are genuinely independent.

For protocols, the lesson is that reserve assets should be chosen with care. Holding large amounts of another stablecoin as backing introduces a direct contagion channel. Using diversified, low-correlation collateral and maintaining high transparency helps contain a depeg before it becomes a cascade.

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