详解 Liquity 的去中心化借贷新玩法，能否后来居上？
Explain in detail Liquity's new decentralized lending method, can it come from behind?
逐一分析 Liquity 的主要特点：零利率、抵押率低、可直接赎回、清算损失少以及质押可以获得额外收入。
The main characteristics of Liquity are analyzed one by one: zero interest rate, low mortgage rate, direct redemption, less liquidation loss and additional income from pledge.
原文标题：《Liquity 的机制真的能实现后来居上？》 撰文： Footprint 翻译：区块链研习社
The original title: "Can Liquity's mechanism really achieve the goal of catching up with others? [Author: Footprint Translation: Block Chain Learning Society
DEX 和 Lending 作为 DeFi 项目的两大基石，在区块链市场中占据着重要的地位。Lending 中除了占据市场龙头地位的 Aave 和 Compound 以外，Liquity 重新定义了 Lending 的玩法。
DEX and Lending, the two cornerstones of the DeFi project, occupy an important position in the blockchain market, with Liquity redefining the Lending play, in addition to the market leaders Aave and Compound.
DEX 和 Lending 作为 DeFi 的两大基石，在区块链市场中占据着重要的地位。Lending 除了占据市场龙头地位的 Aave 和 Compound 以外，2021 年 3 月获得 600 万美元 A 轮融资的 Liquity 以其创新的机制，重新定义 Lending 项目的新玩法，经过五月份极端行情的考验，证明了其机制的有效性。目前 ETH 锁仓量约 40 万枚，约 16 亿美元。
In addition to Aave and Compound, the market leaders, Liquity, which received $6 million in Series A funding in March 2021, has redefined the Lending program with its innovative mechanism, which has been tested by extreme market conditions in May. The extreme market conditions in May have proven the effectiveness of its mechanism. The current ETH lock-up is around 400,000 coins, or approximately $1.6 billion.
ETH 锁仓量（自 2021 年 5 月），数据来源：Footprint Analytics
ETH lock-up (since May 2021), data source: Footprint Analytics
Liquity 除了提供可以通过抵押 ETH 以获得稳定币 LUSD 的借贷业务外，还提供另外两个池子可以帮助用户获取额外的收益：存入稳定池 LUSD 从而划分被清算用户的 ETH，同时获取 Liquity 的代币 LQTY 奖励；质押 LQTY 从而获取用户借贷和赎回时的费用。
In addition to offering the ability to borrow and lend by pledging ETH for the stable coin LUSD, Liquity also offers two other pools to help users earn additional revenue: deposit the stable pool LUSD to divide the liquidated user's ETH and receive Liquity's token LQTY rewards; pledge LQTY to receive fees when the user borrows and redeems.
从 Liquity 官方的 Docs 中，其特点主要包括：
From Liquity's official Docs, its characteristics mainly include:
利率为 0%
The interest rate is 0%
利率为 0%
The interest rate is 0%
110% 的最低抵押率
A minimum mortgage rate of 110%
110% 的最低抵押率
A minimum mortgage rate of 110%
可直接赎回
Can be redeemed directly
可直接赎回
Can be redeemed directly
清算损失小于 10%
Less than 10% of liquidation loss
清算损失小于 10%
Less than 10% of liquidation loss
可存入 LUSD 或质押 LQTY 获得额外收入
Additional income can be obtained by depositing LUSD or pledging LQTY
可存入 LUSD 或质押 LQTY 获得额外收入
Additional income can be obtained by depositing LUSD or pledging LQTY
这些特点，真的如其所说吗？
Are these characteristics really what they said?
本文将结合 Footprint Analytics 已有数据，从以上这 5 个角度出发，逐一展开分析。
This article will combine the existing data of Footprint Analytics, and analyze them one by one from the above five angles.
利率为 0%
The interest rate is 0%
Liquity 仅支持 ETH 作为抵押物进行借款，协议提供无息贷款，Liquity 称比其他借贷系统更高的资本效率。利率方面确实是 0%，但作为借款人更关心的是因借款产生的综合费率。
Liquity only supports ETH as collateral for borrowing and the agreement offers interest free loans, which Liquity claims are more capital efficient than other lending systems. It is true that the interest rate is 0%, but as a borrower you are more interested in the combined rates incurred as a result of borrowing.
因此不可忽略的是：在借款时会产生一笔借款费用，费率一般在 0.5%-5%，根据算法计算费率，上线半年基本维持在 0.5%，唯一抬升是在五月份极端行情前后，最高约为 1.16%。
Therefore, it cannot be ignored: a borrowing fee will be incurred when borrowing, the rate is generally in the range of 0.5%-5%, according to the algorithm to calculate the rate, online six months basically maintained at 0.5%, the only increase is around the extreme market in May, the highest is about 1.16%.
借款人如果在不被清算的情况下，虽无需支付借款利率，实际需承担一次性借款费用，用户综合费率仍然在借款金额的 0.5%-5%，借款人不会因时间拉长而不断增多借款费用，反而可以通过拉长时间来摊薄费用，如果只是短期的行为折算成年化，将是一个较高的费率。因此，Liquity 更加鼓励借款人进行长期借款。
Borrowers who are not liquidated will not have to pay the borrowing rate, although they will actually have to bear a one-off borrowing fee. The combined user rate will still be in the range of 0.5%-5% of the amount borrowed, and borrowers will not have to keep increasing their borrowing fees as time stretches out, but can instead dilute their fees by stretching them out over time, which would be a higher rate if only short-term actions were discounted to adult. Liquity therefore provides a greater incentive for borrowers to borrow over a longer period of time.
110% 最低抵押率
110% minimum mortgage rate
在 Liquity 借款时需开设一个金库（Trove）并向其中存入一定数量的抵押品（ETH），根据抵押的 ETH，可提取自定义数量的 LUSD，但要保证抵押率必须高于 110%。当抵押率小于 110% 时将被清算。虽然 110% 的抵押率更为有效地利用了存入的 ETH，但还有哪些容易被忽略的信息呢？
When borrowing from Liquity you need to open a Trove and deposit a certain amount of collateral (ETH) into it, depending on the ETH pledged, a customised amount of LUSD can be withdrawn, but only if the collateral ratio is above 110%. When the collateral ratio is less than 110% it will be liquidated. While the 110% collateralisation rate is a more efficient use of the deposited ETH, what other information can be easily overlooked?
首先， 上文提到借款费（Borrowing Fee）和清算准备金（Liquidation Reserve）也会被算入抵押率中。
First of all, the above-mentioned Borrowing Fee and Liquidation Reserve will also be included in the mortgage rate.
因此，可以参考下图示例，总的借款金额为 2210 LUSD，官方给出的抵押率为 110%（0.6710 * 3622.92/2210 * 100%），但实际借到手可以使用的金额为 2000 LUSD，按实际可用算抵押率应该为 121%（0.6710 * 3622.92/2000 * 100%）。
Thus, for example, the total amount borrowed is 2210 LUSD and the official collateral ratio is 110% (0.6710 * 3622.92/2210 * 100%), but the actual amount borrowed and available is 2000 LUSD, so the collateral ratio should be 121% (0.6710 * 3622.92/2000 * 100%) based on actual availability. (100%).
由于清算准备金为固定金额，且如果未发生清算，会在还款时还给借款人，因此清算准备金在未被清算时并不算是费用，借款人也可以通过提高借款金额来降低因为借款准备金而被拉高的实际抵押率。
As the liquidation reserve is a fixed amount and will be paid back to the borrower upon repayment if liquidation does not occur, the liquidation reserve is not considered a charge when it is not liquidated and the borrower can also reduce the effective charge ratio that is driven up by the borrowing reserve by increasing the amount borrowed.
数据来源：https://eth.liquity.fi/
Source: https://eth.liquity.fi/
其次， Liquity 会有一个恢复模式（Recovery Mode），当系统的总抵押率（TCR）低于 150% 时将启动恢复模式，对所有抵押率在 150% 以下的用户进行清算，所以在借款时，官方也有提示建议抵押率保持在 150% 以上，以避免在恢复模式下被清算。
Secondly, Liquity will have a Recovery Mode. When the total collateral rate (TCR) of the system is lower than 150%, the recovery mode will be started to liquidate all users with collateral rate below 150%. Therefore, when borrowing money, the Government also has a prompt to suggest that the collateral rate should be kept above 150% to avoid liquidation under the recovery mode.
再次，用户还可以随时将 LUSD 兑换为 ETH，此行为被称为赎回（Redemption），系统会从此时抵押率最低的金库开始赎回，借款人的金库会同时减少抵押品和负债，虽然被赎回不会使用户发生净损失，但会失去部分 ETH 头寸。因此，为避免被赎回需要保持相对其他人更高的抵押率。
Thirdly, users can also exchange LUSD for ETH at any time. This behavior is called Redemption. The system will redeem from the vault with the lowest mortgage rate at this time. The borrower's vault will reduce collateral and liabilities at the same time. Although redemption will not cause net losses to users, it will lose some ETH positions. Therefore, in order to avoid redemption, it is necessary to maintain a higher mortgage rate than others.
因此，虽然在借款时最低的抵押率是 110%，但为了保证账户不被清算或被赎回，抵押率至少要保持在 150% 以上才更为安全。通过 Footprint Analytics 的数据分析，Liquity 的 TCR 即使在极端行情时，经过清算及恢复模式后也能迅速重返到 300% 以上。目前 TCR 也保持在 300% 左右。可以看到，虽然最低可以 110% 的抵押率，但用户为保证抵押品的安全性仍会选择接受较高的抵押率，此时就需要用户在 300% 的抵押率和更高的资金利用率之间做权衡。
Therefore, although the minimum collateral ratio at the time of borrowing is 110%, it is safer to maintain a collateral ratio of at least 150% in order to ensure that the account is not liquidated or foreclosed upon. Using Footprint Analytics data, Liquity's TCR has been able to return to over 300% quickly after liquidation and recovery mode, even during extreme market conditions. The TCR is also currently at around 300%. As you can see, although a minimum collateralisation rate of 110% is possible, users will still choose to accept higher collateralisation rates to ensure the safety of their collateral, which requires a trade-off between a 300% collateralisation rate and higher capital utilisation.
总抵押率（自 2021 年 4 月），数据来源：Footprint Analytics
Total mortgage rate (since April 2021), data source: Footprint Analytics
虽然 TCR 较高，但 110% 的最低抵押率相对于其他更高抵押率的协议来说，对被清算带来的损失也会相应减少，这部分也将在下文详细分析。
Although TCR is relatively high, the 110% minimum mortgage rate will reduce the losses caused by liquidation compared with other agreements with higher mortgage rate, which will also be analyzed in detail below.
可直接赎回
Can be redeemed directly
用户可以用 LUSD 随时按面值赎回相关抵押品，上文中也有提及，但由于赎回时需支付 0.5%-5% 费用，同样这一费用会根据最近赎回的时间及赎回的金额进行调整，只有在 LUSD 的金额小于 1 美元时，用户才会通过赎回 LUSD 从中套利，用户可用小于 1 美元价格的 LUSD 兑换 1 美元价值的 ETH 而从中获利。因此，是套利的空间大还是支付的手续费更多，还需要用户根据当时 LUSD 的价格自行衡量，通过 Footprint Analytics 的数据来看，由于 Liquity 创始人 Robert Lauko 所说的「硬锚定」及「软锚定」的机制，LUSD 每天的价格波动基本稳定的 0.99-1.02 美元之间。
Users can redeem the underlying collateral with LUSD at any time at par, as mentioned above, but as there is a 0.5%-5% fee on redemptions, again this fee is adjusted depending on when the redemption was most recently made and the amount redeemed, users will only be able to take advantage of this by redeeming LUSD for less than $1. Users can redeem LUSD for less than $1 for $1 worth of ETH and take advantage of this. The user can redeem LUSD at less than $1 for $1 worth of ETH and make a profit. Therefore, whether there is more room for arbitrage or more fees to be paid is a matter for the user to gauge based on the price of LUSD at the time. 1.02 USD.
LUSD 价格（自 2021 年 7 月），数据来源：Footprint Analytics
LUSD Prices (since July 2021), Source: Footprint Analytics
从被赎回人的角度，虽然他们在被赎回时未遭受净损失，但抵押 ETH 借款的用户大多都是 ETH 的信仰者，多数认为 ETH 是长期上升的，当他们金库中的 ETH 被减少，实际是减少了之后因 ETH 上涨而使资产增值的可能性。
From the point of view of the redeemed, although they did not suffer any net losses when they were redeemed, most of the users who mortgaged ETH loans are ETH believers, and most believe that ETH is rising for a long time. When the ETH in their vaults is reduced, the possibility of asset appreciation due to the rise of ETH is actually reduced.
因此赎回的行为，对于想从中套利的人来说，只有当 LUSD 小于 1 美元且套利收获大于赎回费时才有意义；对于被赎回人来说，赎回行为也并不太受欢迎。不过 Liquity 通过此机制多提供了一个可以套利的方式，也可以使 LUSD 的价格稳定在 1 美元左右，并通过提升抵押率最低的金库，保持总抵押率在较高的水平。
Redemptions therefore only make sense for those who want to arbitrage from them if the LUSD is less than $1 and the arbitrage gain is greater than the redemption fee; redemptions are also not very popular for the redeemed. Liquity, however, offers an additional way to arbitrage through this mechanism, which also allows the price of LUSD to stabilise at around $1 and keeps the total collateral ratio at a high level by boosting the lowest collateralised vault.
清算损失小于 10%
Less than 10% of liquidation loss
当抵押率小于 110% 时，Liquity 会通过清算抵押品偿还了债务，借款人将失去了抵押物 ETH，清算会导致借款人的抵押品美元价值净损失 9.09％（=100％ * 10/110）。
When the mortgage rate is less than 110%, Liquity will repay the debt by liquidating the collateral, and the borrower will lose the collateral ETH. Liquidation will result in a net loss of 9.09% (= 100% * 10/110) of the US dollar value of the borrower's collateral.
另外，在借款时还有一笔 200 LUSD 的清算准备金，当发生清算时，200 LUSD 的清算准备金会被发起清算者获得。清算准备金在借款时虽然不需要用户额外支付，但会被计算在债务中，在计算金库的抵押率时也会被计算在内，因此仍以上图存入金库的金额为例。当因为价格波动导致抵押率下降到 110% 以下发生清算时，此时被清算的抵押物对应的价值并不是借款人手里拥有的 2000 LUSD 的 110%，而是总债务 2210 LUSD 对应 110% 的美元价值。此时借款人失去了所有的 ETH，手里只剩下 2000 LUSD，按照 ETH 被清算时的价格计算，借款人实际损失率为 17.73%，即：
In addition, there is a liquidation reserve of L200 USD at the time of borrowing, which is captured by the originator of the liquidation in the event of liquidation. The liquidation reserve does not require additional payment by the user at the time of borrowing, but it is counted as part of the debt and is also taken into account in the calculation of the vault's collateral ratio, so the amount deposited into the vault is still shown above as an example. When the collateral ratio falls below 110% due to price fluctuations and liquidation occurs, the value of the liquidated collateral is not 110% of the 2000 LUSD held by the borrower, but 110% of the total debt of 2210 LUSD in USD. At this point the borrower loses all of the ETH and is left with only 2000 LUSD in hand, giving the borrower an effective loss ratio of 17.73% at the price of the ETH at the time of liquidation, i.e.
(0.671 * 3622.92-2000)/(0.671 * 3622.92) * 100%
(0.671 * 3622.92-2000)/(0.671 * 3622.92) * 100%
当然不同的借款金额计算的实际损失率也不相同，较高的借款金额会降低因清算准备金而拉高的损失率。
Of course, the actual loss rate calculated by different loan amounts is also different. Higher loan amounts will reduce the loss rate increased by liquidation reserves.
虽然由于清算准备金的因素可能使被清算的损失率并不比设想中的小，但相比于 MakerDAO 要求的 150% 抵押率来说，Liquity 的机制已经是一个很大的进步，对于借款人来说，因为价格波动而发生被清算的安全空间也多出了 40%。
While the liquidation reserve factor may not make the loss ratio for liquidation smaller than envisaged, Liquity's mechanism is a significant improvement over the 150% collateral ratio required by MakerDAO and provides borrowers with 40% more safety margin in the event of liquidation due to price fluctuations.
存入 LUSD 或质押 LQTY 获额外收入
Deposit LUSD or pledge LQTY to obtain additional income.
Liquity 除了提供借贷可以借入 LUSD 以外，还提供了提高资金利用率的 LUSD 稳定池和质押 LQTY 以获得收益的池子。存入稳定池 LUSD 可以按其在池中的占比分得被清算用户的 ETH，以及奖励 Liquity 的代币 LQTY；从稳定池中获得的 LQTY 又可以再进行质押，从而获取用户借贷和赎回时的费用。
In addition to providing loans to borrow LUSD, Liquity also provides LUSD stabilization pools to improve the utilization rate of funds and pools to pledge LQTY to obtain profits. The LUSD deposited in the stable pool can obtain the ETH of the liquidated user and the token LQTY for rewarding Liquity according to its proportion in the pool. LQTY obtained from the stable pool can be pledged again, thus obtaining the expenses for users to borrow and redeem.
稳定池会获得 ETH 和 LQTY，获得 ETH 与被清算的情况相关，获得 ETH 的同时存入池子的 LUSD 会被销毁。由于被清算时抵押率为 110%，用户在被销毁 1 LUSD 的同时，会获得价值 110% 美元对应的 ETH，用户可从中获利 10%。如果此时 ETH 继续下降使刚刚获得 1.1 美元价值的 ETH 降到 1 美元以下，用户将发生浮亏。为防止这种可能，B.Protocol 为 Liquity 的稳定池提供者自动将 ETH 转换回 LUSD，并将其存回稳定池，为用户锁定清算利润，节省 gas 成本。但如果用户是长期看好 ETH 的信仰者，可能在未来资产得以升值。
The stabilisation pool will receive ETH and LQTY, the acquisition of ETH is linked to the liquidation and the LUSD deposited in the pool will be destroyed at the same time as the ETH is acquired. As the collateralisation rate is 110% at the time of liquidation, the user will receive $110% of the value of the ETH at the same time as 1 LUSD is destroyed, giving the user a 10% profit. If at this point the ETH continues to fall so that the ETH that has just gained $1.1 in value falls below $1, the user will incur a loss. To prevent this possibility, B.Protocol's stabilisation pool provider for Liquity automatically converts the ETH back to LUSD and deposits it back into the stabilisation pool, locking in liquidation profits for the user and saving gas costs. However, if the user is a long-term believer in ETH, the asset may be able to appreciate in value in the future.
然而作为稳定币更重要的还是看它的用例，目前铸造出的 6 亿多 LUSD 在 Liquity 稳定池中的总量超过 75%，在外部的流动不足 2 亿。在 Liquity 借款的用户兜兜转转仍是在 Liquity 中投资，整个系统的用例像是一个套娃，其可持续性有待验证。
However, as a stable currency, it is more important to look at its use cases. At present, the total amount of more than 600 million LUSD minted in the Liquity stable pool exceeds 75%, and the external flow is less than 200 million. Users who borrow money from Liquity are still investing in Liquity. The use case of the whole system is like a doll, and its sustainability needs to be verified.
LUSD 总流通量（自 2021 年 4 月），数据来源：Footprint Analytics
Total LUSD in circulation (since April 2021), data source: Footprint Analytics
Liquity 的创始人 Robert Lauko 在 7 月 2 日回应，稳定池中的 LUSD 是在大量的 LQTY 激励下用户的理性选择，后续 LQTY 代币激励会减少，用户会因此改变策略。
Robert Lauko, founder of Liquity, responded on July 2 that LUSD in the stable pool is a rational choice for users under a large number of LQTY incentives. Subsequent LQTY token incentives will be reduced and users will change their strategies accordingly.
稳定池获得的另一个奖励是 LQTY，由于不是治理代币，LQTY 唯一的用例是捕获协议的借款费和赎回费，只有在借款和赎回发生较多时，LQTY 才能获取更多收益。因此，反而是整个系统不太稳定的时候才更有利于提升 LQTY 的价值。可以看到目前每日从质押 LQTY 获得的 ETH 和 LUSD 也并不算多。
Another bonus that the stable pool receives is LQTY. As it is not a governance token, the only use case for LQTY is to capture the borrowing and redemption fees of the agreement, and LQTY only gains more when more borrowings and redemptions occur. Therefore, it is rather when the overall system is less stable that it is more beneficial to increase the value of LQTY. As you can see the daily ETH and LUSD from pledged LQTYs is not very high at the moment.
质押 LQTY 累计获得的收益（自 2021 年 4 月），数据来源：Footprint Analytics
Pledged LQTY Accumulated Earnings (since April 2021), Data Source: Footprint Analytics
在五月中旬受到币价波动的影响，借款和赎回的行为增多，LQTY 在此期间捕获的收益快速增长。从 6 月开始，从 LUSD 的总流通量可以看出，用户的借款和赎回行为下降，LQTY 不论是捕获 LUSD 还是 ETH 的能力都明显下降。
Borrowing and redemptions increased in mid-May due to the volatility of the currency and LQTY's capture of proceeds increased rapidly during this period. From June onwards, as evidenced by the total LUSD circulation, user borrowing and redemptions declined and LQTY's ability to capture both LUSD and ETH declined significantly.
随着后续 LQTY 代币激励逐渐衰减，LUSD 如果能更多的拓展它的用例，从而吸引更多用户进行借贷，Liquid 的 TVL 保持持续上升趋势，LQTY 的价值也许值得期待。
With the gradual decline of subsequent LQTY token incentives, if LUSD can expand its use cases more, thus attracting more users to borrow, Liquid's TVL will continue to rise, and the value of LQTY may be worth looking forward to.
结语
Conclusion
通过对 Liquity 的 5 个角度的分析，在不同立场会有不同的解读，也促使它在行情剧烈震荡下仍能保持稳健收益。从借款人的角度出发，不论是从借款综合费率还是被清算的损失率，更大的借款金额和拉长时间更能摊薄成本和损失。
An analysis of Liquity's 5 perspectives, which will be interpreted differently from different positions, also contributes to its ability to maintain solid returns despite the dramatic market shocks. From the borrower's perspective, larger borrowing amounts and longer timeframes are more likely to dilute costs and losses, both in terms of the combined borrowing rate and the loss rate of being liquidated.
但从各个角度来看，Liquity 都在不断完成它的机制，创新的清算机制使它从效率和抵押率等方面都有别于 MakerDAO，Footprint 团队也将在之后的文章中对比分析 Liquity 与 MakerDAO。LUSD 的用例从 9 月开始也在不断向外部渗透，让我们更加期待 LUSD 真正成为一个可广泛应用，占有市场份额的去中心化稳定币的一天。
The LUSD use case has been percolating since September and we are looking forward to the day when The LUSD use case has been penetrating since September and we are looking forward to the day when LUSD becomes a widely used decentralised stablecoin with market share.
