A stablecoin is a type of cryptocurrency where the value of the digital asset is supposed to be pegged to a reference asset, which is either fiat money, exchange-traded commodities (such as precious metals or industrial metals), or another cryptocurrency.

In theory, 1:1 backing by a reference asset could make a stablecoin value track the value of the peg and not be subject to the radical changes in value common in the market for many digital assets. In practice, however, stablecoin issuers have yet to be proven to maintain adequate reserves to support a stable value and there have been a number of failures with investors losing the entirety of the (fiat currency) value of their holdings.

Background 
Stablecoins have several purported purposes. They can be used for payments and are more likely to retain value than highly volatile cryptocurrencies. In practice, many stablecoins have failed to retain their "stable" value.

Stablecoins are typically non-interest bearing and therefore do not provide interest returns to the holder.

Reserve-backed stablecoins
Reserve-backed stablecoins are digital assets that are stabilized by other assets. Furthermore, such coins, assuming they are managed in good faith and have a mechanism for redeeming the asset(s) backing them, are unlikely to drop below the value of the underlying physical asset, due to arbitrage. However, in practice, few, if any, stablecoins meet these assumptions.

Backed stablecoins are subject to the same volatility and risk associated with the backing asset. If the backed stablecoin is backed in a decentralized manner, they are relatively safe from predation, but if there is a central vault, it may be robbed or suffer loss of confidence.

Fiat-backed 
The value of stablecoins of this type is based on the value of the backing currency, which is held by a third party–regulated financial entity. Fiat-backed stablecoins can be traded on exchanges and are redeemable from the issuer. The stability of the stablecoin is equivalent to the cost of maintaining the backing reserve and the cost of legal compliance, licenses, auditors, and the business infrastructure required by the regulator.

In this setting, the trust in the custodian of the backing asset is crucial for the stability of the stablecoin's price. If the issuer of the stablecoin does not actually possess the fiat necessary to make exchanges, the stablecoin can quickly lose value and become worthless.

The most popular stablecoin, Tether, initially claimed to be fully backed by fiat currency; this was proven to be untrue, and Tether was fined $41 million by the Commodity Futures Trading Commission for deceiving consumers. Instead, Tether only had enough fiat reserve to guarantee 27.6% of their stablecoin. Nevertheless, Tether still remains widely used.

Cryptocurrencies backed by fiat currency are the most common and were the first type of stablecoins on the market. Their characteristics are:
 Their value is pegged to one or more currencies (most commonly the US dollar, the euro, and the Swiss franc) in a fixed ratio;
 The value connection is realized off-chain through banks or other types of regulated financial institutions which serve as depositaries of the currency used to back the stablecoin;
 The amount of the currency used to back the stablecoin should reflect the circulating supply of the stablecoin.

Examples: TrueUSD (TUSD), USD Tether (USDT), USD Coin, Monerium EURe.

In January 2023, National Australia Bank (not Australia's central bank) announced that it would create by mid-2023 an Australian Dollar fiat-backed stablecoin called the AUDN, for streamlining cross-border banking transactions and trading carbon credits.

Commodity-backed 
The main characteristics of commodity-backed stablecoins are:
 Their value is fixed to one or more commodities and redeemable for such (more or less) on demand;
 There is an implied or explicit promise to redeem by unregulated individuals, agorist firms, or even regulated financial institutions;
 The amount of commodity used to back the stablecoin should reflect the circulating supply of the stablecoin.

Holders of commodity-backed stablecoins can redeem their stablecoins at the conversion rate to take possession of the backing assets under whatever rules as to timing and amount are in place at the time of redemption. Maintaining the stability of the stablecoin is the cost of storing and protecting the commodity backing.

Cryptocurrency-backed 
Cryptocurrency-backed stablecoins are issued with cryptocurrencies as collateral, conceptually similar to fiat-backed stablecoins. However, the significant difference between the two designs is that while fiat collateralization typically happens off the blockchain, the cryptocurrency or crypto asset used to back this type of stablecoins is done on the blockchain, using smart contracts in a more decentralized fashion. In many cases, these allow users to take out a loan against a smart contract via locking up collateral, making it more worthwhile to pay off their debt should the stablecoin ever decrease in value. In addition, to prevent sudden crashes, a user who takes out a loan may be liquidated by the smart contract should their collateral decrease too close to the value of their withdrawal.

Significant features of crypto backed stablecoins are:
 The value of the stablecoin is collateralized by another cryptocurrency or a cryptocurrency portfolio;
 The peg is executed on-chain via smart contracts;
 The supply of the stablecoins is regulated on-chain, using smart contracts;
 price stability is achieved by introducing supplementary instruments and incentives, not just the collateral.

The technical implementation of this type of stablecoins is more complex and varied than that of the fiat-collateralized kind, which introduces a greater risk of exploits due to bugs in the smart contract code. With the tethering done on-chain, it is not subject to third-party regulation creating a decentralized solution. The potentially problematic aspect of this type of stablecoins is the change in the value of the collateral and the reliance on supplementary instruments. The complexity and non-direct backing of the stablecoin may deter usage, as it may take time to comprehend how the price is ensured. Due to the highly volatile and convergent cryptocurrency market, substantial collateral must also be maintained to ensure stability.

Live stablecoins projects of this type are Havven (the pair: nUSD stablecoin and HAV the collateral-backed nUSD), DAI (pair: CDP Collateralized Debt Position and MKR governance token used to control the supply) and others. There is also Wrapped Bitcoin (WBTC), see BitGo.

Seigniorage-style/algorithmic stablecoins (not backed)
Seigniorage-style coins, also known as algorithmic stablecoins, utilize algorithms to control the stablecoin's money supply, similar to a central bank's approach to printing and destroying currency. Seigniorage-based stablecoins are a less popular form of stablecoin.

Algorithmic stablecoins are a type of stablecoin intended to hold a stable value over the long term because of particular computer algorithms and game theory rather than a peg to a reserve asset. In practice, some algorithmic stablecoins have yet to maintain price stability. For example, the "UST" asset on the Terra blockchain was theoretically supported by a reserve asset called "Luna", and plummeted in value in May 2022. Wired magazine said, "The Ponzinomics were just too obvious: When you pay money for nothing, and stash your nothing in a protocol with the expectation that it will give you a 20 percent yield—all you end up with is 20 percent of nothing."

Significant features of seigniorage-style stablecoins are:
 Adjustments are made on-chain,
 No collateral is needed to mint coins,
 Value is controlled by supply and demand through algorithms, stabilizing the price.

Basis was one example of a seigniorage-style coin.

TerraUSD (UST), created by Do Kwon, was meant to maintain a 1:1 peg with the United States dollar. Instead of being backed by dollars, UST was designed to keep its peg through a complex system connected with another Terra network token, Terra (LUNA). In May 2022 UST broke its peg with its price plunging to 10 cents, while LUNA fell to "virtually zero", down from an all-time high of $119.51. The collapse wiped out almost $45 billion of market capitalization over the course of a week.

On 13 June 2022, Tron's algorithmic stablecoin, USDD, lost its peg to the US Dollar.

Possible advantages 
The Bank of International Settlements lists the possible merits of the subject as enhancement of anti-money laundering efforts, operational resilience, customer data protection, financial inclusion, tax compliance, and cybersecurity.

Risks and criticisms

Lack of regulation 
Nellie Liang, Under Secretary of the Treasury for Domestic Finance reported to the Senate banking committee that the rapid growth of the stablecoin market capitalization and its potential for financial services innovation require urgent congressional regulation.

Lack of transparency 
Tether is currently the world's largest market capitalization stablecoin. It has been accused of failing to produce audits for reserves used to collateralize the quantity of minted USDT stablecoin. Tether has since issued assurance reports on USDT backing, although some speculation persists.

De-pegging 
Many projects can advance a product and call it a stablecoin. Thus, despite the name, many stablecoins have historically needed more stability because digital assets can be built to many different standards. Stablecoins such as TerraUSD, USDD, DEI and others crashed to zero in 2022 alone.

Other concerns 
Griffin and Shams' research attributed the creation of unbacked USDT to the rise in Bitcoin's price in 2017. Following that, research indicated little to no evidence that Tether USD minting events influenced Bitcoin values unless they were publicized to the public by Whale Alert.

Failed and abandoned stablecoin projects
A number of stablecoins have crashed or lost their peg. For example:
 The stablecoin project Basis, which had received over $100 million in venture capital funding, shut down in December 2018, citing concerns about US regulation.
 On 11 May 2022, Terra's stablecoin UST fell from $1 to 26 cents. The subsequent failure of Terraform Labs resulted in the loss of nearly $40B invested in the Terra and Luna coins. In September 2022, South Korean prosecutors requested the issuance of an Interpol Red Notice against the company's founder, Do Kwon. 

Diem (formerly Libra) was abandoned by Facebook/Meta and later purchased by Silvergate Capital.

References

Cryptocurrencies
스테이블코인(Stablecoin)은 달러화 등 기존 화폐에 고정 가치로 발행되는 암호화폐를 말한다.

역사 

2019년 1월, 핀테크회사 BXB(비엑스비)는 세계 최초로 담보통화로 원화를 채택한 스테이블코인 KRWb을 출시한다고 밝혔다. 크립토 KRWb는 원화와 1:1 비율로 연동된다.

2019년 2월 25일, 중국 정부는 최근 급부상한 스테이블 코인이 주로 미국의 달러와 연동되는 시장상황에 경계심을 높이고 있다. 실제로 스테이블 코인을 개발할 때는 '1코인=1달러'를 유지할 수 있도록 설계하는 경우가 가장 많다.

2019년 3월 1일, 일본 최대 금융기관 미즈호 파이낸셜 그룹(Mizuho Financial Group)이 자체 발행 엔화 연동 암호화폐 '제이코인(J-Coin)'를 공개할 예정이다. J코인의 가치는 1엔당 1코인으로 스테이블하게 고정된다.

세계 최대 SNS인 페이스북도 자사 메신저 송금서비스에 이용할 스테이블코인인 가칭 페이스북 코인을 자체 개발할 계획이다.

스타트업 리저브(Reserve)가 40개 암호화폐 관련 업체 의견을 정리한 ‘2019 스테이블코인 현황: 안정적, 글로벌, 디지털 화폐를 위한 경쟁에서의 과장 대 현실’이라는 보고서를 발표했다. 보고서는 “스테이블코인은 잠재적으로 수조 달러(약 수천조원) 규모 시장이 될 것”이라며 “미국 달러가 앞으로 1~2년 내에 암호화폐 공간에서 토큰화된 가장 유동성이 높은 자산(tokenized liquid asset)이 될 것”이라고 전망했다.

암호화폐 거래소 제미니(Gemini)의 창업자 윙클보스(Winklevoss) 형제는 포춘과의 인터뷰에서 "스테이블 코인(stable coin)과 실제 자산으로 뒷받침되는 STO(증권형 토큰 발행)가 2019년 암호화폐 핵심 키워드가 될 것"이라고 예측했다.

2019년 2월 14일, JPM 코인을 성공적으로 발행하고, 테스트 했다고 밝혔다. 미국 대형 은행 중 최초로 JP 모건이 JPM 코인을 2019년에 발행할 계획이다. 달러화에 고정된 가치의 스테이블코인이다. JP모건체이스는 세계 최대 금융기관이다. JP 모건은 매일 전세계적으로 일어나는 결제 비즈니스 규모가 매일 6조달러에 이르는 미국 최대 은행이다. 그러자, JP모건체이스의 최대 경쟁사인 골드만삭스도 스테이블코인을 발핼할 것이라고 밝혔다. 달러화에 고정된 스테이블코인을 발행하려면, 발행량과 동일한 액수의 달러화 현금을 보유해야만 한다. 따라서, 세계 최대 은행인 두 은행의 스테이블코인 발행은, 현금보유능력을 고려한다면, 상당한 의미가 있다. 두 은행 모두 세계 최고 주식부자 워렌 버핏이 몇조원씩 주식을 보유하고 있다. 워렌 버핏은 미국 상위 5위 대형 은행 중 4개 은행의 주식을 대규모로 보유하고 있다.

테더 

스테이블코인 중 가장 유명한 것은 테더이다. 시가총액 기준 10위 안에 들어간다. 수많은 암호화폐 거래소에 상장되어 있어서, 스테이블코인 중 지배적인 위치에 있다. 1달러=1테더로 고정가치인데, 가격이 폭락하면서, 신뢰성이 크게 흔들린 적이 있지만, 다른 스테이블코인은 전세계의 수많은 거래소에 상장된 경우가 없다.

2018년 11월 20일, 블룸버그통신은 미국 법무부가 스테이블코인의 대표 주자인 테더(tether, USDT)를 이용한 가격 조작 의혹에 대해 수사 중이라고 보도했다. 테더는 달러와 1:1의 교환 비율을 유지하는 암호화폐다. 미 연방 검찰은 트레이더들이 올해 초 암호화폐 거래소 비트파이넥스에서 비트코인 가격을 불법 조종하기 위해 테더를 사용한 것으로 의심하고 있다. 비트파이넥스와 테더는 모두 동일한 경영진이 운영하고 있으며, 새로운 암호화폐는 대부분 비트파이넥스를 통해 시장에 나온다. 비트파이넥스가 스테이블코인 '테더'를 이용해 비트코인 가격을 1300% 상승시켰다는 혐의를 두고 관련자를 수사하고 있다. 비트파이넥스의 본사는 홍콩에 있으며, 영국령 버진아일랜드 국적이다. 미국 법무부가 구체적 증거를 포착한 것으로 알려졌다. 테더는 대부분 거래사이트에서 거래되지만 주로 홍콩계 자본이 운영하고 있는 비트피넥스에서 많이 거래된다. 비트피넥스는 테더를 가장 많이 보유하고 있는 것으로 알려졌다.

2018년 9월, 28억 달러 규모의 테더가 유통되고 있고 암호화폐 전체 시장 규모로 8위다. 루이스 프리 FBI 전 국장이 설립한 법률 회사 FSS는 테더가 발행량 만큼의 달러 잔액을 보유하고 있다고 확인해 줬다.

스테이블 코인의 종류
모든 스테이블 코인은 4 가지 기본 유형으로 나눌 수 있다.
 법정화폐 담보 스테이블코인 - 법정 화폐(주로 미국 달러) 기반되며 중앙화된다. 여기에는 USDT, USDC, TUSD, BUSD가 포함된다.
  상품 담보 스테이블 코인 - 금(석유, 기타 귀금속)이 지배하는 교환 거래 상품으로 확보되며 중앙화된다. 예: DGX, PAXG, XAUT.
 암호화폐 담보 스테이블코인 - 다른 암호화폐 기반 스테이블 코인이다. 이들이 출범한 주된 이유는 일반적인 암호화폐보다 가격 역학에서 더 안정적인 분산형 토큰을 얻고자 하는 바람이었다. 예: DAI, EOSDT.
 알고리즘 기반 스테이블코인(비담보, 상층화) - 담보 없이 분산형이지만, 중앙은행의 통화 발행 접근법과 유사하게 스테이블코인 총량을 관리하는 알고리즘을 통해 가격 안정을 달성한다. 예: UST, USDN, FEI

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각주 

암호화폐