Introduction: Why Do We Need a Liquidity Pool?

In traditional finance, trading relies on order books and matching engines, which are often centralized in centralized trading platforms. In the world of decentralized finance (DeFi), trading needs to be conducted entirely on-chain, while avoiding the custody and trust risks brought about by centralization. Liquidity pools, as a non-intermediary solution, are reshaping the model of financial transactions. As the locked value of the DeFi ecosystem continues to grow, liquidity pools have become the core technology in this field due to their simplicity and powerful functionality.

What is the liquidity pool?

Simply put, a liquidity pool is a set of funds locked in a smart contract designed to support decentralized trading, lending, and other on-chain financial activities.

Users, known as liquidity providers (LPs), provide liquidity to the market by depositing two equivalent tokens into a liquidity pool and earn profits from transaction fees. For example, inUniswapOn the platform, users can easily provide liquidity for a trading pair (such as ETH/USDT) and enjoy fee sharing.

For example:

• Suppose you and your friend opened an ‘exchange shop’ together, specializing in exchanging apples and oranges.
• Each of you puts 100 apples and 100 oranges on the counter of the ‘exchange shop’, which is a ‘liquidity pool’.
• If a customer wants to exchange 10 apples for oranges, he just needs to put the apples on the counter and can take the corresponding number of oranges from the counter without the need for both of you to operate personally.
• Each time a transaction is made, customers need to pay a small fee, such as 0.3 apples, these fees will be stored in the ‘exchange shop’ and distributed to you as a reward for providing liquidity.

This counter is a ‘liquidity pool’, and you two are ‘liquidity providers (LP)’.

The design of this mechanism eliminates the dependence on intermediary institutions in traditional finance. Anyone can participate and withdraw liquidity at any time, bringing users a brand new trading experience.

The difference between a liquidity pool and a traditional order book

In traditional exchanges like Gate.io, trading relies on order books to match the buying and selling needs of both parties. Buyers and sellers need to find counterparts one by one to complete the transaction.

In a liquidity pool, there is no need for buyers and sellers to match directly. Tokens are stored in the pool, and users only need to ‘trade’ with the pool to complete the exchange. This model makes trading more efficient, especially when trading for less popular assets.

Traditional order book vs. Liquidity pool example:

• Order Book Mode: You want to buy second-hand books at a flea market, but you need to find someone willing to sell this book.
• Flea market sets up a ‘second-hand book exchange counter’ in the funds pool mode, where anyone can put books in it and others can exchange the books they want at any time (the exchange follows certain value rules, not just any book can be exchanged for another). This method does not require you to search for trading partners one by one.

How does the liquidity pool operate?

Assuming a user wants to exchange USDT (USD stablecoin) for ETH (Ethereum), it can be done through a liquidity pool like Uniswap.

1. Deposit Funds: Liquidity providers (such as yourself) deposit 6000 USDT and 2 ETH into the liquidity pool, creating a pool at the current market price (assuming 3000 USDT = 1 ETH).
2. Transaction process: A user wants to buy 1 ETH with 3000 USDT. The liquidity pool will automatically adjust. The user deposits 3000 USDT into the pool and withdraws 1 ETH from the pool.
3. Price Change: After the transaction is completed, the balance in the liquidity pool becomes 9000 USDT and 1 ETH, causing the price of ETH to rise to a higher level, reflecting the market supply and demand relationship.

Liquidity providers profit from the transaction fees generated by trading (such as 0.3% of the transaction amount) while also taking on certain risks (detailed in the following text).

The primary purpose of a liquidity pool

1. Automated Market Maker (AMM)

AMM is one of the core applications of liquidity pools. For example, on Uniswap, you can exchange USDT for ETH without waiting for a seller to come online and place an order. The AMM algorithm adjusts the price based on the quantity of tokens in the pool to ensure smooth transactions.

Real Case:

In the traditional order book system, if you want to buy a bottle of milk tea, you would ask the boss, ‘Who can sell me milk tea?’ In the AMM model, the boss has already prepared the inventory, and the price of milk tea is directly determined by the inventory quantity.

2. Liquidity Mining and Yield Generation

Through liquidity mining, users can deposit tokens into liquidity pools and earn additional tokens rewarded by the platform. For example, inPancakeSwapBy depositing CAKE tokens, you can earn more CAKE or other reward tokens (staking for new token offerings).

3. Governance and Voting

Some platforms use liquidity pool tokens for governance voting. For example, users who provide liquidity to the pool receive LP tokens, which can be used to vote on platform policies or directions.

4. Smart Contract Insurance

DeFi projects often face the risk of smart contract vulnerabilities. Through the insurance services provided by liquidity pools, users can obtain a certain level of financial protection. For example,Nexus MutualThe platform allows users to provide insurance protection for potential contract vulnerabilities.

5. Synthetic asset minting

For example, users deposit ETH as collateral into a liquidity pool, and through the combination of an oracle and smart contract, synthetic assets anchored to gold or the US dollar are generated. This allows users to trade tokenized versions of various real assets on the blockchain.

Risks and Challenges of Liquidity Pool

1. Impermanent Loss

If you provide liquidity for the USDT/ETH fund pool and the price of ETH rises significantly, you may find that holding ETH directly can be more profitable than participating in the fund pool.

For example:

By depositing 100 USDT and 0.1 ETH into the liquidity pool, the price of ETH doubled. Although the total value of the pool increased, the amount of tokens you receive in your hand may be less than when held separately, which is impermanent loss.

2. Setting the price range in the liquidity pool

In the traditional Automated Market Maker (AMM) model, liquidity providers (LPs) typically need to provide liquidity across the entire price range, for example from 0 to infinity. Although this mechanism is simple, it may lead to the majority of liquidity being concentrated in inactive price areas, wasting the efficiency of fund utilization.

To address this issue, some platforms (such as Uniswap V3) have introduced the concept of ‘concentrated liquidity’, allowing LPs to set a specific price range for the liquidity they provide. This way, liquidity only operates within the preset price range, significantly improving the efficiency of capital utilization.

Example:

Assuming you provide liquidity for the ETH/USDT trading pair:

• If you think the price of ETH will fluctuate between 3000 USDT and 4000 USDT, you can lock the liquidity within this price range.
• When the price of ETH falls within this range, the fund pool will use your liquidity to complete the transaction, and you will also earn fees as a result.
• If the ETH price falls outside of this range, your liquidity will be temporarily unable to participate in trading until the price returns to the range.

In this way, liquidity providers can manage funds more accurately and improve yield efficiency. However, this also increases the complexity of setting price ranges, especially for novices, requiring more market analysis and judgment.

The larger the price range you set, the lower the capital utilization rate, and the greater the risk of impermanent loss you will bear (for example, if ETH keeps rising, the ETH tokens you invest will completely turn into USDT)

Smart Contract Risk
If there is a vulnerability in the smart contract of the liquidity pool, hackers may steal assets from the pool. For example, some platforms have been attacked due to contract vulnerabilities, resulting in heavy losses for users.

Centralization Risk
Some project development teams may have the management authority over the fund pool, which may lead to the possibility of malicious tampering.

Summary: The future and development of the liquidity pool

Liquidity pool has become one of the core technologies in the DeFi ecosystem, providing users with new ways of decentralized trading, yield generation, and asset management. Through innovative smart contracts, they have the potential to change the way traditional finance operates. However, newcomers need to carefully evaluate the risks when participating, choose reputable and secure platforms, and ensure the safety of their funds.