Stablecoins represent one of the most consequential experiments in modern finance: an attempt to create privately issued digital money that maintains parity with government-backed currencies while operating on decentralised networks. With billions traded daily and a consolidated market exceeding $165 billion, they now sit in the same weight class as large regional banks - yet their stability mechanisms range from the boringly prudent to the structurally doomed.
Nearly ten years after Tether launched as the first stablecoin in 2014, the landscape has evolved into a complex ecosystem of competing designs, each with distinct risk profiles. The collapse of TerraUSD in May 2022 wiped out tens of billions of dollars and underscored just how fragile some of these designs are. The temporary depegging of USDC during the Silicon Valley Bank crisis in March 2023 demonstrated that even well-collateralised stablecoins can be destabilised by events in the traditional banking system.
Understanding the mechanisms behind stablecoin stability - and the specific conditions under which those mechanisms fail - is essential for anyone operating in cryptocurrency markets. This analysis examines the four primary backing models, the critical role of arbitrage, detailed case studies of catastrophic depeg events, and the regulatory and design principles that may determine which stablecoins survive the next crisis.
How Stablecoins Maintain Their Peg
A stablecoin "peg" is a fixed value relationship with a more stable asset - typically the U.S. dollar - maintained through designed mechanisms. This acts as a value anchor: for every stablecoin issued, there should be a corresponding mechanism ensuring it can be redeemed at or near $1.00. The specific mechanism varies dramatically between designs, and the differences determine whether the peg holds under stress or shatters catastrophically.
All pegs, fundamentally, are narratives - stories explaining why two non-identical assets should trade interchangeably. The quality of that story, and the reserves and mechanisms backing it, determines whether the peg survives when markets turn hostile.
Fiat-Collateralised
Backed 1:1 by reserves of fiat currency held in bank accounts or short-term government securities. Each token can theoretically be redeemed for one dollar. Tether (USDT) and USD Coin (USDC) are the dominant examples. Trust depends on the quality, liquidity, and verifiability of reserves through regular audits.
Crypto-Collateralised
Over-collateralised with other cryptocurrencies to hedge against volatility. DAI requires depositing crypto assets exceeding the stablecoin's face value - providing a buffer. The trade-off: capital inefficiency and correlation risk with the broader crypto market.
Commodity-Backed
Linked to physical commodities like gold or precious metals. Pax Gold (PAXG) represents ownership of a specific quantity of gold. These offer intrinsic value and inflation protection, but liquidity can be constrained by the underlying commodity market.
Algorithmic
Rely solely on smart contracts and automated market mechanisms to adjust coin supply in response to demand. No direct asset backing. TerraUSD and Basis used algorithms to mint or burn tokens (create new coins or destroy existing ones to manage supply and push the price back toward $1). This design has proven structurally fragile under extreme market conditions.
A fifth emerging approach - hybrid collateral models - combines assets from multiple categories (fiat, crypto, and commodities) to create diversified backing. By spreading risk across uncorrelated asset types, hybrid models aim to maintain stability even when individual collateral categories experience stress. This approach offers more resilient foundations than single-collateral strategies, though it adds operational complexity.
The Role of Arbitrage in Peg Stability
Arbitrage is the invisible engine that keeps stablecoin prices anchored. When a stablecoin trades above or below its peg, arbitrageurs exploit the price difference between primary and secondary markets, and in doing so, push the price back toward $1.00. The efficiency of this mechanism is arguably more important than any other single factor in maintaining peg stability.
The primary market is where stablecoins are minted and redeemed at a fixed exchange rate of one dollar to one token. The secondary market refers to trading on cryptocurrency exchanges, where prices can fluctuate above or below the peg.
above $1.00
(primary market)
(secondary market)
back to $1.00
The reverse works symmetrically: when a stablecoin trades below $1.00, arbitrageurs buy it cheaply on exchanges and redeem it at the issuer for one full dollar, reducing circulating supply and pushing the price upward. Easy access to both the deposit/redemption process and readily available arbitrage capital are necessary conditions for a stable peg.
The Tether-Ethereum Migration: A Natural Experiment
Research examining Tether's migration from the Omni blockchain to Ethereum in April 2019 provides compelling evidence for the centrality of arbitrage access. Ethereum's larger investor community and faster transaction processing dramatically increased the number of unique addresses interacting with the Tether Treasury. Following the migration, deviations from Tether's pegged price decreased by approximately 50%, and the time required to correct deviations shrank from six days to three.
The finding is consistent with a straightforward hypothesis: increasing access to arbitrage trades is the single most important factor in stablecoin stability. Anything that makes arbitrage faster, cheaper, or more accessible strengthens the peg; anything that impedes it creates vulnerability.
DAI and the Case for Safe Collateral
The decentralised stablecoin DAI offers another instructive case. Initially, DAI could only be issued through risky ETH collateral - meaning its price fluctuations correlated directly with Ethereum's volatility. After extreme fluctuations in March 2020, MakerDAO began allowing users to deposit safer collateral types, including the USDC stablecoin issued by Circle.
In December 2020, MakerDAO introduced a Peg Stability Module (PSM), enabling users to swap one USDC for one DAI directly with the MakerDAO treasury. This facilitated a powerful arbitrage mechanism: when DAI trades at a premium relative to USDC, users can swap USDC for DAI and sell the DAI on the secondary market for a profit, bringing the price closer to parity. After the PSM's introduction, deviations from DAI's peg decreased by up to 50 basis points - a substantial improvement in stability.
The Money Market Fund Model
The lowest-risk stablecoin designs essentially replicate money market funds on distributed ledgers. These funds invest in short-duration, high-quality commercial paper or government-backed securities, aiming to provide liquidity on demand with minimal risk. Translating this model to cryptocurrency involves substituting fast databases with slower distributed ledgers, enabling individual unit transfers without redemption, and - in the case of most issuers - capturing 100% of the interest income as management fees.
Circle's USDC exemplifies this approach, maintaining backing through cash and short-duration U.S. government securities. The model appears mundane compared to algorithmic alternatives - and that is precisely the point. The boring nature means operators cannot extract seigniorage income (profit earned by issuing currency that costs less to produce than its face value - in this context, pocketing yield from reserves while paying users nothing) through digital alchemy, and it suggests a lower probability of value vaporisation under stress conditions.
Regulatory engagement represents a distinguishing characteristic of this model. Both USDC and Paxos' USDP actively court regulatory oversight, accepting compliance requirements - including Know Your Customer (KYC) and anti-money laundering (AML) protocols - that reduce product attractiveness to certain users but significantly increase institutional credibility. For money market stablecoins, the peg story holds that users can theoretically return tokens to operators at any time for redemption at par value - and the reserves exist to honour that promise.
Actual Use Cases
Contrary to marketing materials suggesting broad monetary utility, stablecoins serve primarily specialised applications within the cryptocurrency ecosystem. The dominant use case involves collateralising leveraged cryptocurrency investments, particularly perpetual futures contracts. These derivative products attract exchanges seeking fee revenue, institutions requiring capital efficiency, and retail participants desiring high leverage ratios.
An emerging application involves programmable money within decentralised finance protocols. Current DeFi implementations focus primarily on facilitating cryptocurrency borrowing and lending to enable increased trader leverage. Some protocols create financial structures characterised by unsustainable yield promises funded through token appreciation rather than productive economic activity - a pattern that bears uncomfortable resemblance to Ponzi structures with additional complexity layers.
Looking ahead, however, there are legitimate opportunities for stablecoin growth. International money transfers currently involve excessive ceremony and cost dictated by existing banking infrastructure rather than fundamental requirements. Stablecoins pegged to the euro and U.S. dollar could unlock new avenues for cross-border trading, remittances, and integration with the global financial architecture - if they can demonstrate sufficient stability and regulatory compliance.
Catastrophic Depegging Events
Stablecoin depegging incidents have occurred repeatedly, with some landmark events sending shockwaves through the entire cryptocurrency ecosystem. Given stablecoins' pivotal role in daily trading - with billions of dollars flowing through them - decoupling events do not merely affect the stablecoin itself; they can trigger domino effects across markets, erode confidence, create liquidity crises on exchanges, and disrupt the DeFi applications that depend on stablecoins for collateral and settlement.
In an earthquake-like event for the crypto industry, Terra's flagship algorithmic stablecoin UST suddenly lost its peg to the U.S. dollar. Prior to the collapse, Terra's native token LUNA had a market capitalisation of $40 billion. UST ranked as the third-largest stablecoin with $18 billion in assets.
Terra maintained its peg through a sister token called Luna, which represented equity claims in Terra's distributed ledger operations. Luna's purported value derived from expectations that Terra Labs would collect ongoing fees from developers using the blockchain - supplemented by Anchor, an automated lending programme promising 19.5% annual yields on stablecoin deposits. This yield represented aggressive user acquisition: participants received equity (Luna tokens) for platform usage, which created apparent growth, which increased perceived equity value, which funded additional subsidies - a classic circular dependency (the system's value rested entirely on belief in itself, with no external anchor to halt a reversal).
When Terra Labs announced subsidy reductions in early May, users stopped participating, Luna equity value declined, peg pressure emerged, and further Luna selling created a death spiral (a self-reinforcing loop where falling prices trigger more selling, which pushes prices lower still, with no floor). Within two weeks, both tokens had effectively reached zero. Tens of billions in value evaporated permanently. Concurrently, other stablecoins including Tron's USDD and Near Protocol's USN were destabilised, revealing the fragility of market trust in the entire stablecoin sector.
Following the collapse of Silicon Valley Bank, Signature Bank, and Silvergate Bank, two major stablecoins experienced temporary but alarming depegging. Circle, the issuer of USDC, disclosed that $3.3 billion of its cash reserves were held at SVB - leading to a sharp devaluation of over 12% for USDC in a matter of hours.
Simultaneously, DAI's value was dragged down due to its significant exposure to USDC within its collateral portfolio. Market panic subsided only when the Federal Reserve intervened to protect bank depositors, and both USDC and DAI subsequently regained their dollar pegs. The episode demonstrated a crucial vulnerability: even fully collateralised stablecoins are only as safe as the banking institutions holding their reserves.
Tangible's stablecoin USDR attempted to establish a robust peg through an innovative collateral mix of tokenised real estate and DAI stablecoin, with an auto-recollateralisation mechanism using rental income. Despite the creative design, on October 11th a sudden surge in redemption requests drained all liquid DAI reserves. The tokenised real estate collateral, using the illiquid ERC-721 NFT standard, could not be liquidated quickly enough to meet demand.
The inability to honour rapid redemptions sparked fear, accelerated withdrawals, and ultimately broke the peg. USDR's failure illustrated that even seemingly robust collateral mechanisms can fail when liquidity mismatches exist - a lesson that echoes traditional bank run dynamics applied to novel digital asset structures.
Equity-Backed and Fraud-Backed Models
The Structural Problem with Seigniorage Models
Equity-backed stablecoins - sometimes misleadingly labelled "algorithmic" to suggest software predictability during growth while deflecting blame onto code during collapse - face a fundamental design flaw. Their critical engineering challenges are financial, not computational. In a seigniorage model (one where the protocol issues its own governance or equity token as the shock absorber, using that token's perceived value to defend the stablecoin's peg), the backing asset is not dollars or gold: it is confidence.
The core concept involves a business maintaining ledgers of debts owed to counterparties while allowing debt transfers. Confidence in debt face value is maintained through reference to equity value - as long as equity substantially exceeds outstanding debts, and equity holders absorb impairments before debt holders, the debt should maintain value. This principle operates in traditional finance: Netflix bonds maintain value because the market believes Netflix equity would absorb losses first. In stablecoin terms, seigniorage shares (the protocol's own governance tokens, used as a shock absorber when the stablecoin loses its peg) play the role that Netflix equity plays for bondholders - they are supposed to take the first loss.
The critical difference in stablecoin applications: these debts must be instantly transferable and redeemable without requiring actual repayment over extended periods. This failure mode appears inevitable for seigniorage models because no business can sustainably maintain high equity value relative to "all money anywhere." As adoption increases, the stablecoin becomes a growing threat to the backing business's equity. The collateral here is endogenous (its value is generated internally by the same system it is supposed to protect - not by any independent external asset), which means it loses value precisely when the stablecoin needs protection most. Superior performance accelerates rather than mitigates this threat.
In plain terms: these systems worked only as long as people believed they would work. When confidence cracked, the collateral lost value at the same moment the protocol needed it most - a self-reinforcing collapse with no circuit breaker. The mint/burn arbitrage mechanism (where traders are incentivised to create or destroy the governance token to push the stablecoin back toward $1) that was designed to restore the peg instead became the engine of destruction, flooding the market with newly minted governance tokens as the price fell.
Fraud-Backed Models
The final category involves stablecoins claiming money market fund backing while systematically misrepresenting reserve composition and accessibility. This model involves maintaining the appearance of full reserves while the actual composition may differ from representations. Resource availability at scale enables purchasing substantial regulatory cover, and as long as operations generate profits, scrutiny remains manageable. The financial scale supports defensive investments while maintaining operational viability.
Mitigation Strategies and the Regulatory Path Forward
When stablecoins lose their peg, market participants, issuers, and regulators must act swiftly to mitigate damage and restore confidence. The historical case studies point toward clear principles for more resilient stablecoin design and regulation.
- 1 Full Collateralisation with Liquid Reserves - Stablecoins should be fully backed by liquid dollar reserves. This ensures smooth functioning of the arbitrage mechanism that helps maintain the pegged value, even during market turbulence or speculative attacks. The reserves must be genuinely liquid - tokenised real estate and illiquid NFTs do not count.
- 2 Real-Time Proof-of-Reserve Audits - Independent verification of reserve assets at regular intervals, utilising proof-of-reserve systems, reduces the likelihood of runs and mitigates the risk of issuers misrepresenting their holdings. Real-time or near-real-time auditing is technically feasible and should become a baseline expectation.
- 3 Decentralised Arbitrage Access - Easy access to deposit and redemption processes with the stablecoin issuer, combined with readily available arbitrage capital, are necessary conditions for a stable peg. Barriers to arbitrage - whether technical, regulatory, or financial - create vulnerability.
- 4 Safe Collateral Requirements - Backing stablecoins with risky, correlated crypto assets creates peg instability. Introducing safe collateral types (cash equivalents, short-term government securities) and mechanisms like MakerDAO's PSM demonstrably reduces deviations from the peg.
- 5 Regulatory Oversight and Transparency - Regulatory bodies including the U.S. Treasury and Federal Reserve are already exploring frameworks for digital currency regulation and the potential of central bank digital currencies (CBDCs) to complement or replace privately issued stablecoins. More rigorous rules on reserve management and disclosure requirements would strengthen the credit foundation across the sector.
- 6 Diversified Collateral Structures - Hybrid collateral models that combine fiat, crypto, and commodity assets provide diversification against single-asset failures. Strategic allocation across uncorrelated asset types reduces the impact of volatility on stablecoin value and establishes more resilient foundations than single-collateral approaches.
The core lesson from every depegging event: stablecoins that rely on narratives, incentive schemes, or algorithmic adjustments without genuine, liquid, verifiable reserves are not stable at all - they are leveraged bets on continued confidence. When confidence breaks, it breaks completely, and the unwind is measured in billions of dollars and days, not basis points and weeks.
Depegging Timeline
Key Takeaways
- Stablecoins maintain their peg through four primary models: fiat-collateralised, crypto-collateralised, commodity-backed, and algorithmic - each with fundamentally different risk profiles
- Arbitrage is the engine of peg stability: easy access to mint/redeem at par combined with readily available capital are the necessary conditions for maintaining $1.00
- Tether's migration to Ethereum reduced peg deviations by ~50% and correction time from six days to three - demonstrating that blockchain efficiency directly affects stability
- MakerDAO's introduction of safe collateral and the Peg Stability Module measurably reduced DAI's deviations, proving that collateral quality matters more than algorithmic complexity
- Terra UST's $48B+ collapse demonstrated the inevitable failure mode of equity-backed stablecoins when value depends on adoption rather than sustainable reserves
- Even well-collateralised stablecoins (USDC) can depeg when their banking partners fail - stablecoins are only as safe as the institutions holding their reserves
- USDR's collapse showed that illiquid collateral (tokenised real estate) cannot support redemptions during a crisis, regardless of the collateral's long-term value
- Full collateralisation with liquid reserves, real-time proof-of-reserve audits, and decentralised arbitrage access form the foundation of resilient stablecoin design
- Hybrid collateral models combining fiat, crypto, and commodities offer diversification benefits but add operational complexity
- The stablecoin market is evolving toward greater transparency, regulatory engagement, and potential integration with CBDCs - the designs that survive will be those built on verifiable reserves, not narratives
Research Desk, PolyMarkets Investment, May 6, 2024