What Really Happens When a Digital Dollar Breaks the Buck

The Peg Is a Promise, Not a Law

Nothing in a stablecoin’s code holds its price at $1, meaning that the peg is simply an economic promise where the issuer says every token can be redeemed for one real dollar, and arbitrage does the rest. If USDT trades at $0.99, professional traders buy it at a discount and redeem it with Tether for $1.00, pocketing the difference and pushing the market price back up.

Conversely, if it trades above $1, they mint new tokens for exactly $1 and sell them. The market price stays pinned only because that redemption machine is believed to work.

In practice, the redemption machine has a narrow doorway. Tether, for instance, requires verified customers and a $100,000 minimum to redeem directly, while Circle (USDC’s issuer) works through institutional accounts. Everyone else (be it the retail holder, the DeFi protocol, the offshore exchange) depends on a chain of arbitrageurs having both the access and the nerve to keep buying discounted tokens during a panic.

That structure is why depegs happen on exchange screens even when the issuer never misses a redemption, i.e. the peg’s first line of defense is other people’s confidence, not the reserves themselves.

Four Depegs, Four Different Causes

The October 2018 USDT scare was a confidence problem where rumors about the solvency of Tether and its affiliated exchange Bitfinex sent USDT down to roughly $0.88 on some venues. Reserves ultimately met redemptions, and the peg healed within days.

The March 2023 USDC depeg was more of a banking problem, as Circle disclosed that $3.3 billion of its reserves sat at the failed Silicon Valley Bank, resulting in the token falling to $0.87 before U.S. regulators guaranteed the bank’s deposits. It bears mentioning that the episode dragged down the decentralized finance (DeFi) market as a whole, with DAI, heavily collateralized by USDC, sliding to about $0.89.

The November 2025 xUSD collapse was a counterparty problem, and it’s the freshest reminder that yield-bearing stablecoins carry risks the giants don’t. Stream Finance’s xUSD wasn’t backed dollar-for-dollar in a bank account because it ran leveraged strategies through outside fund managers to generate yield for holders.

When one of those managers disclosed a $93 million loss, Stream froze withdrawals and xUSD cratered from $1 to as low as $0.24 within hours (with $160 million in user deposits being frozen).

Last but not least, the May 2022 terraUSD (UST) collapse emanated from a design problem, and it’s the one that never came back. UST held its peg not with reserves but with an algorithmic seesaw against its sister token LUNA (burn $1 of LUNA, mint one UST, and vice versa).

When large withdrawals knocked UST off $1, holders rushed to convert to LUNA and sell, hyperinflating LUNA’s supply and vaporizing the very asset meant to back the peg. UST fell below $0.10 within a week and trades near $0.02 today. Roughly $40 billion across the two tokens evaporated, and the collapse dragged down hedge funds, lenders, and, eventually, the FTX exchange’s fragile empire with it.

2026: Contraction, Then a Stabilizing Floor

This year’s stress so far has looked nothing like a flash crash but rather a slow leak with a regulatory cause. After new U.S. federal stablecoin rules wiped out interest payments on digital dollars, yield-seeking capital started walking away. The category opened 2026 at $310 billion, climbed to roughly $320 billion by mid-April, and topped out near $322.1 billion in mid-May.

From there, the metrics reversed hard, with the total stablecoin supply shedding $14.56 billion by the start of August, the sharpest contraction since Terra’s collapse. USDT slipped from roughly $189 billion to $183.2 billion over the same stretch (after gaining $5 billion earlier in the year while rivals shed $4.2 billion). USDC, meanwhile, fell from a March peak near $80 billion to about $72.1 billion.

The pullback wasn’t limited to the two giants, given that in early July $1.9 billion worth of volume was erased, with Sky Dollar’s USDS posting the sharpest weekly decline even as Paypal’s PYUSD and Ripple’s RLUSD kept gaining.

Shrinking supply doesn’t translate directly into a depeg, but it thins the buffer of arbitrage capital that absorbs shocks, which is precisely what gets tested when the next scare arrives.

Why Concentration Raises the Stakes

That buffer is also unevenly distributed since USDT and USDC alone still account for roughly 83% of the entire $307.6 billion stablecoin market, meaning the redemption machinery that keeps the whole category pinned to $1 runs through two companies’ balance sheets and banking relationships.

That concentration means that even though the two coins dominate trading, which is generally a stabilizing factor, it also results in shocks to either issuer (such as a banking failure like Circle’s in 2023, a regulatory action, or a reserve dispute), causing immense unforeseeable damage.

How to Read the Next Depeg

Firstly, it is important to check the cause itself because reserve-backed coins (knocked off the peg by fear or a banking hiccup) tend to always snap back once redemptions are proved out. However, designs that have relied on their own token (à la TerraUSD), or on an opaque yield strategy, can’t.

Second, investors can watch redemption patterns, not just price, since a coin trading at $0.97 (while the issuer processes withdrawals normally) is simply doing so at a discount, not carving out a death spiral.

Third, it is imperative to watch where the contagion is flowing, given USDC’s wobble repriced DAI within hours, Terra’s failure reached companies that never touched UST, and xUSD’s collapse rippled through DeFi lenders holding it as collateral.