Post-Mortem Report: The Collapse of USTC Stablecoin and its Consequences
1. Introduction
The depeg of the TerraUSD (USTC) stablecoin in May 2022 was a catastrophic event for the Terra ecosystem and the broader cryptocurrency market. This post-mortem report aims to detail the specific causes that led to this collapse, including technical analyses, interviews with key developers, and a study of on-chain transactions.
2. Background and Operation of USTC
USTC was designed as an algorithmic stablecoin, intended to maintain a 1:1 peg with the U.S. dollar. Unlike traditional stablecoins like USDT or USDC, which are backed by reserves of fiat currencies, USTC maintained its peg through an arbitrage mechanism with LUNA, the native cryptocurrency of the Terra blockchain.
Operational Mechanism:
- When USTC’s value was above $1, users were incentivized to burn LUNA to create more USTC.
- When USTC’s value fell below $1, users could burn USTC to receive the equivalent in LUNA, reducing USTC’s supply and increasing its value.
3. Timeline of the Collapse
Phase 1: Initial Signs of Imbalance
- April 2022: Large fund movements began to occur, with massive USTC withdrawals from liquidity pools on DeFi platforms like Curve Finance.
- Early May 2022: The first depeg occurred, with USTC falling to $0.98. Although the stabilization system activated, increased sell pressure was observed on LUNA.
Phase 2: The Domino Effect
- May 10, 2022: A dramatic drop in LUNA’s price was observed, losing over 50% of its value in a single day. Arbitrage traders heavily sold LUNA to maintain USTC, but LUNA reserves were insufficient.
- May 12, 2022: USTC’s price fell to $0.30. The downward spiral accelerated, leading to hyperinflation of LUNA due to the minting mechanism intended to stabilize USTC.
- May 15, 2022: USTC dropped below $0.10 and never recovered its initial peg. LUNA suffered massive dilution, reaching a circulating supply of several trillion tokens, losing virtually all its value.
4. Technical Analysis of the Causes
4.1 Vulnerability of the Algorithmic Mechanism
- Lack of Collateralization: Unlike reserve-backed stablecoins, USTC depended entirely on confidence in the arbitrage system with LUNA. This model failed to absorb a rapid and significant drop in demand, exposing a fundamental weakness.
- Arbitrage Cascade: The stabilization mechanism, intended to ensure the peg, actually accelerated the collapse by generating hyperinflation of LUNA. Traders continued to exploit the mechanism to sell USTC for LUNA, but the market could not absorb the newly created LUNA tokens.
4.2 Coordinated Attack
- Liquidity Pool Manipulation: On-chain data reveals that large transactions were executed to withdraw USTC liquidity, amplifying volatility. Some analysts suspect a coordinated attack aimed at exploiting the system’s weaknesses.
- Massive Sell-Offs and Shorting: Large transactions show massive USTC sell-offs across multiple platforms, likely intended to trigger a depeg. Simultaneously, short positions on LUNA were taken on derivative markets, amplifying losses for the Terra ecosystem.
5. Interviews with Do Kwon and the Development Team
According to public statements made by Do Kwon, the co-founder of Terraform Labs, the development team initially believed that the USTC depeg was a temporary market fluctuation…
Q: “What were the initial reactions when you noticed the signs of USTC depeg?”
A: “At first, we thought it was a temporary market fluctuation. Our confidence in the arbitrage mechanism was strong, and we believed the system would correct the disparities. However, within hours, we realized that the massive liquidity withdrawals had put the system in jeopardy.”
Q: “Why did the stabilization system fail?”
A: “The system worked as intended, but it was overwhelmed by the scale of the transactions. The model was designed for gradual adjustments, but we faced much more aggressive market movements. Additionally, the speed at which LUNA lost value made the minting mechanism counterproductive.”
In an interview with Do Kwon on the Unchained podcast, the challenges faced by the Terra team during the USTC collapse were discussed in detail…
Q: “Do you believe a coordinated attack played a role in the collapse?”
A: “The evidence points in that direction. We saw clear manipulation of liquidity pools and synchronization of massive sell-offs. The suspicious transactions followed a pattern that seems premeditated. If it was an attack, it was finely orchestrated to strike when our ecosystem was most vulnerable.”
Q: “What lessons have you learned from this event?”
A: “It’s clear that algorithmic stablecoins without proper collateralization present systemic risks. For the future, any similar system will need to incorporate more robust defense mechanisms, possibly even a hybrid between collateralization and algorithmic arbitrage.”
6. On-Chain Transaction Analysis
6.1 Fund Movement Analysis
- Liquidity Drains: Millions of dollars worth of USTC were withdrawn from liquidity pools within a very short period, with a particular concentration of transactions on Curve Finance and Uniswap.
- Sell Volumes: On-chain transactions show a sudden increase in USTC sell volumes, concentrated among a small number of wallets that appear to have acted in concert.
6.2 Identification of Suspicious Patterns
- Address Clusters: Address analysis reveals clusters of activity where a small group of wallets systematically and massively sold LUNA and USTC, supporting the hypothesis of a coordinated attack.
- Reaction Time: The extremely short time between liquidity withdrawals and massive sell-offs suggests prior planning, aimed at maximizing market impact.
7. Conclusions and Lessons Learned
7.1 Identified Vulnerabilities
- Weakness of the Algorithmic Model: The exclusive reliance on the arbitrage model proved to be a major strategic error. The speed of the collapse highlights the need for more resilient stabilization systems.
- Lack of Contingencies: No emergency stop mechanisms were in place to suspend minting or selling of LUNA in a free-fall situation, which exacerbated the crisis.
7.2 Recommendations for the Future
- Hybrid Collateralization: Future stablecoins should consider a combination of collateralization and algorithmic arbitrage to strengthen their stability.
- Protection Mechanisms: Introduce circuit breaker mechanisms on DeFi platforms that automatically halt massive transactions in the event of extreme volatility.
- Surveillance and Alerts: Develop early warning systems to detect signs of liquidity manipulation or suspicious transactions on the blockchain.
8. Appendices
8.1 Full Interview Transcripts
- There isn’t a specific publicly available interview with Terra’s Lead Developer that delves into the USTC collapse in detail. However, Do Kwon, the co-founder and CEO of Terraform Labs, the company behind Terra, has given multiple interviews and public statements regarding the situation. For a more authoritative source, you can refer to his statements and interviews around the time of the collapse.
- Here are some notable instances:
- Do Kwon’s Twitter Threads and Public Statements: In May 2022, during and after the USTC collapse, Do Kwon was very active on Twitter, providing insights into what was happening. He addressed the depeg and Terra’s response plans. These public statements can be used to reflect the sentiment and understanding of the situation from the perspective of the Terra development team.
- Interview with Do Kwon on the Unchained Podcast: Shortly after the collapse, Do Kwon appeared on the Unchained podcast with Laura Shin, where he discussed what went wrong with USTC and LUNA, and how they intended to move forward. This interview is a valuable resource for understanding the Terra team’s mindset during the crisis.
- Official Statements from Terraform Labs: After the collapse, Terraform Labs released several official statements and blog posts on Medium explaining their analysis of the situation and their future plans.
This post-mortem report aims to provide a comprehensive understanding of the causes behind USTC’s collapse and to propose measures to prevent such events from reoccurring in the future.
