什么是无常损失以及如何预估
什么是AMM？
在加密领域中，AMM模式由Bancor首先实践，由Uniswap率先实践成功，AMM英文为Automated market maker，意为自动做市商模式，它是相对于传统中心化交易所的做市商模式来说的，AMM相当于是去中心化的做市商模式，人人都可以成为流动性提供商。AMM模式中，流动性提供者可以获得手续费收益，同时也面临“无常损失”的风险。与Uniswap类似，欧易 Swap最核心的规则为资产池中两种资产数量之积为定值X*Y=K。
什么是无常损失？
用户向Swap资金池添加流动性后，当价格上涨或者下跌时，由于恒定常数自动做市商(AMM)的定价模型的机制，用户撤出流动性后所得的资产与单纯持有相比会出现一定的损失，这个损失叫做无常损失。
无常损失是如何发生的？
无常损失的发生与AMM的机制有关，例如当OKT的价格为50 USDT时，假设用户A向流动性池中添加10 OKT与 500 USDT，此时用户A的总资产价值1000USDT。假设此时流动性池中总的流动性为100 OKT与 5000 USDT, 用户A占总流动性池的10%。
若OKT的价格上涨为 200 USDT，则根据恒定常数自动做市商的机制，总流动性池中资产的量变为50 OKT与10,000 USDT，若此时用户A撤出流动性，因为此前用户A提供的流动性占总流动性池的10%，则用户A成功取出 5 OKT与 1000 USDT，此时用户A的资产价值为2000 USDT(不计手续费收入)。
但若用户A不向流动性池提供流动性，而是单纯持有则用户A的资产应该价值 10*200 + 500 =2500 USDT，中间的损失为500USDT ，提供流动性与单纯持有之间相较产生的损失称为无常损失。无常损失的大小只与提供流动性时币对的价格(P0)与撤出流动性时币对价格(P1)的比值(P1/P0)有关。
但是用户可以通过提供流动性赚取交易的手续费，一定程度上可以弥补价格波动带来的无常损失。
用户可以通过下表预估无常损失：
| 添加流动性后涨跌幅 | 无常损失(添加流动性与单纯持仓相较的损失) |
| -90% | 42.50% |
| -60% | 9.65% |
| -30% | 1.57% |
| -10% | 0.14% |
| 0% | 0.00% |
| 10% | 0.11% |
| 30% | 0.85% |
| 60% | 2.70% |
| 100% | 5.72% |
| 150% | 9.65% |
| 200% | 13.40% |
关于OKTC:
OKTC主页：https://www.okx.com/cn/oktc
欧易 Swap主页：https://www.okx.com/cn/oktc/swap
OKTC文档：https://www.okx.com/cn/oktc/docs/dev/quick-start/overview
GitHub: https://github.com/okx/exchain
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