A trade that fills instantly still has to pull tokens from somewhere. On a shared pool those tokens come from two balances already sitting in a contract, and both balances move when the trade confirms.
The mix-up is that a screenshot of a ticker can hide whether you are hitting that inventory, holding a share of it, or only holding a vote token that happens to share a name with one side of the pair. Fees you thought you earned as a depositor can already have been split between the share and the protocol.
Automated market makers (AMMs) keep two token reserves in a contract and price each swap from those balances, so anyone who can pay gas can trade against the inventory, and anyone who deposits both sides can take a share of the trader-paid fee.
Uniswap liquidity pools are that design. How those two balances keep a product sits in how Uniswap works. The holder picture is the pair itself: two reserves, a share that is separate from UNI, and a permissionless create that starts empty.
After someone else swaps, both reserves have already changed
When a Uniswap swap confirms, one token balance in the pool is higher and the other is lower. You did not put either token in, and the fill still came from those two reserves, because the pool is inventory already sitting in a contract, waiting for the next swap.
Suppose someone sent 80 USDC into a USDC and ETH pair you do not own, and after the fill the USDC side of that contract is larger while the ETH side is smaller. The ETH that left is what paid the trader, because the two balances moved when the swap used them, with no rest bid to hit.
A liquidity pool is a pairing of tokens in a smart contract that is used for swapping on decentralized exchanges. Liquidity providers add tokens to a pool and in return receive UNI-V2 tokens or NFTs that represent their ownership of that liquidity (source: Uniswap Labs, What is a liquidity pool?). You are looking at the pairing, with no LP share in your wallet.
Uniswap manages liquidity pools, each made up of reserves of two ERC-20 tokens, and updates prices based on pool state. Anyone can become a liquidity provider by depositing token pairs into a pool (source: Uniswap Docs, How Uniswap Works). The generic picture of how AMMs work is the category lesson, and Uniswap's pair is the version you are watching.
The constant-product rule is one sentence here: the pool pays out the second token so the product of the two balances still holds, after a v2 fee comes off the input. The full sequence, including a toy size versus a thin pool, sits in that Uniswap-works guide, so you can skip that algebra and still read the fill as long as you see that both sides moved.
A thin pool makes that move larger for the same 80 USDC, and a deep pool makes it smaller. The support page's warning is the holder version of that fact: look at available liquidity before you size a swap. Low inventory is a worse fill, and you can leave, because you never had to deposit to learn that.
The same two tickers on another chain are another pair with their own balances, so a screenshot of Ethereum reserves is a different book from a Base fill. What Uniswap is names the protocol as a competing decentralized exchange (DEX), and a BloFin book is a different venue, while the pool you watched still lives in a contract on one chain.
Hold the picture: two reserves, one swap, both sides already different, and the people who deposited those tokens hold a share you do not have.
The LP share that tracks a deposit sits beside UNI
An LP is someone who deposited the pair so others can swap. The contract mints a share for that slice, and swap fees on that pool can accrue to the share. UNI in a wallet is a vote token, which is a different claim even when both sit in the same app.
| What you hold | What it tracks | What can accrue |
|---|---|---|
| UNI in a wallet | Governance token | No pool swap-fee share |
| v2 LP token | Fungible share of one pair | Fees folded into that pair |
| v3 position | Range NFT | Fees while the market is in range |
Every time someone trades against the pool, each LP that has contributed to the pool earns a portion of the trading fees, proportional to their share of the total liquidity (source: Uniswap Blog, Understanding Liquidity Provision in DeFi). Your 80 USDC paid a fee as a trader, and that fee landed with whoever still holds the share for that pair.
v2 tracks the share as a fungible pool token. The 0.30 percent v2 fee, and how that token compounds inside the pair, sits with Uniswap v2. The holder split here is enough: selling UNI leaves the pair untouched, because the LP token is a separate claim.
v3 tracks a position as an NFT for a chosen band. Fees on that position wait to be collected, which is a bookkeeping change from how v2 folds fees into the two balances. If someone sends you a random v3 NFT, you received a pool position, or a junk wrapper.
People talk about pool yield as if it were a savings rate. Swap-fee share moves with volume, with the fee tier, and with how large your share is versus the rest of the pair. DeFi yield for crypto investors is the generic yield vocabulary. A Uniswap LP share stays two tokens plus a fee stream that moves with volume.
Uniswap's own LP blog is written for people who want to deposit. You can understand the share, leave it unminted, and still read a pool. Creating the pair, which is the next mechanical fact, also skips requiring you to become an LP.
Anyone with gas can create a two-token pool
The protocol does not run a listing committee for ordinary pairs. Anyone who can pay gas can create a pool for two tokens, and the new contract starts empty, so a ticker on the create screen is a label.
Each Uniswap liquidity pool is a trading venue for a pair of ERC-20 tokens. When a pool contract is created, its balances of each token are 0, someone must seed it with an initial deposit of each token before it can facilitate trades, and that first depositor sets the starting price (source: Uniswap Docs, v2 pools). You can watch a pair that still has dust, and the ratio you see is whatever the seeder put in, which can be nonsense next to every other market.
The protocol's services are open for public use, and no one has the ability to restrict who can or cannot use them. The result is that anyone can swap tokens, list a token, or provide liquidity in a pool to earn fees (source: Uniswap Labs, How does the Uniswap protocol work?). Listing here means creating the pair onchain, which is a different event from BloFin turning on a UNI market.
The create call still settles on a chain. On Ethereum that means ETH for gas, even when the pair is USDC and UNI. How Ethereum works is the chain picture. A failed create still burns gas, and a confirmed create with zero reserves still quotes a ratio of nothing useful.
Later versions still let anyone create a pool. For you, the holder fact is the same: a new pool can exist before anyone has a reason to trust the other token. Read the token addresses, rather than the symbol, because a UNI ticker in a fresh pair can be a different ERC-20.
Matching the current ratio when you add to an existing v2 pair, picking ticks, or wrapping ETH are operator steps, and they belong with people who intend to deposit. You only need the permissionless fact so a brand-new pair does not look like an official listing.
Onchain markets on Ethereum is the wider onchain-market picture. Uniswap's factory is one permissionless route inside that picture. The next split is money: who is paid when that 80 USDC crossed the pool.
How swap fees and protocol fees split
A swap fee is charged on the trade and can accrue to LPs whose liquidity is active. Protocol fees are a different slice of some of those swap fees, pointed at the protocol, and holding UNI skips a pro-rata share of protocol revenue.
In Uniswap v2, every pool charges a flat 0.30 percent fee that is automatically added to pool reserves. Protocol fees are a portion of swap fees directed to the protocol rather than to LPs, and they are distinct from the swap fee that accrues to liquidity providers (source: Uniswap Docs, Fees). On v2, that 0.30 percent is the pool's swap fee. After the fee switch, the docs' split on enabled v2 pools is 0.25 percent to LPs and 0.05 percent as protocol fee, so treat those shares as current settings.
v3 lets a pair exist at more than one fee tier, including 0.05 percent, 0.30 percent, and 1 percent. v4 lets a creator set a fee in fine increments, including through extra pool code you do not have to read. Read the pool's fee on the quote.
Protocol fees, when they are on, are a governance-set slice. UNIfication in December 2025 turned protocol fees on for v2 pools and for select v3 pools, with collected value designed to feed UNI burns. Tally proposal 100 is Executed, and its adopted text is to activate protocol fees on a subset of v4 pools on those same chains, rather than on every v4 pool everywhere (source: Uniswap Foundation vote, Activate v4 Protocol Fees (Part 1/2)). A v4 label is separate from proof that protocol fees are on.
UNI holders have no pro-rata claim on that protocol revenue. Burning UNI, or failing to, is a separate token fact. The LP share still earns the LP side of the swap fee on that pool, and collapsing those two cuts is how people think a UNI balance is in the pool.
You can ignore both cuts and still swap. You pay the swap fee as a trader, and you collect it only if you hold the share. The version you are looking at changes where that share sits inside the curve.
A v3 range still holds two tokens inside a band
On v3 the pair is still two tokens. An LP can concentrate the deposit inside a price band instead of across every price, and fees accrue on that position while the market sits in the band. Setting ticks is daily work for a depositor, while seeing that the pool is still two reserves is the holder idea.
The defining idea of Uniswap v3 is concentrated liquidity: liquidity that is allocated within a custom price range (source: Uniswap Docs, Concentrated Liquidity). If the market leaves the band, that position stops earning fees until price comes back. The tokens did not vanish from the protocol. That position is no longer the inventory the swap is pulling from.
You can still swap against whatever liquidity is in range at that moment. A v3 pool can look deep on a chart and still be thin at your size if little capital sits at the current price. That is why the pool on v3 is a set of bands rather than one undifferentiated bucket the way a v2 pair is. The holder read is two tokens, plus a question about whether the inventory you care about is in range.
Tick math, fee-tier picking as daily work, and how to mint a position sit in concentrated liquidity on Uniswap v3. Range orders and which band to choose stay there.
Other AMMs use pools too. Raydium AMM liquidity pools are a Solana-side picture of two-sided inventory, on a different protocol. Curve, on Uniswap's side of the comparison, is a stableswap specialist, Uniswap is the general AMM, and Curve internals sit on Uniswap versus Curve.
v4 still holds two reserves per pool. Extra code on a v4 pool is a hook, which is a different risk surface and a different guide. You skip the singleton layout and still know you are looking at a pair.
If you wanted a rest bid on a book, you wanted a different market structure. Uniswap prices from pool reserves, a book matches rest orders, and the later AMM-versus-book guide covers that contrast. The closer question is which claim you actually hold when you say you are in Uniswap.
Holding UNI and sitting in a pool
A UNI balance, an LP share, and a BloFin UNI market are three claims. You can hold UNI and never touch a pool, swap against a pool and never mint a share, or trade UNI on BloFin and never call a Uniswap contract.
You can watch that pair's two reserves on an explorer without holding UNI, without holding the LP token, and without a BloFin balance. The contract still updates when someone else swaps. A wallet screenshot that only shows UNI is still a UNI balance, even if Uniswap's app is open in the next tab, because the app chrome leaves those three claims as three claims.
BloFin has listed UNI/USDT on spot since January 15, 2024.
BloFin lists two UNI perpetuals: UNIUSDT at up to 75x, listed January 12, 2023, and UNIUSD, an inverse contract settled in UNI, at up to 20x, listed June 27, 2025. Those markets are venue books. They are a different path from your 80 USDC swap on an explorer, and a fill there will stay on the venue ledger.
If the other token in a pool rips away from the one you deposited, the mix you can withdraw later is a different problem from a swap you watched. That inventory risk is impermanent loss on Uniswap. The generic IL lesson is impermanent loss. Naming it here keeps fee share next to inventory risk.
A pool is the wrong next click if you wanted a provide-liquidity walkthrough, a Curve stableswap how-to, or a UNI perpetual primer. It is the right click if you needed two reserves, a share that is separate from UNI, a permissionless create, and a clean split between LP fees and protocol fees. You can close the explorer. You never had to deposit to know what you were looking at.
Frequently asked questions
If I swap UNI and USDC on Base, whose reserves am I hitting?
The Base pair's reserves, rather than Ethereum's. Each pool is a contract on one chain with its own two balances, so same tickers skip sharing inventory. Bridging UNI moves tokens, and it leaves those two pairs as two pairs. Size the quote against the pool the wallet will actually call. An Ethereum reserve screenshot will skip pricing a Base swap. If the interface can switch networks, read the network on the review screen before you sign.
If you transfer a v3 UNI/USDC NFT that still shows uncollected fees, can the old wallet still collect, or does that claim move with the NFT?
It moves with the NFT. The wallet that holds the v3 position NFT owns that liquidity, and that owner is who can claim earned fees on it. After you send the NFT, the receiving wallet can collect those uncollected fees, and the old wallet cannot. Uncollected fees sit on the position the NFT represents. An old-address screenshot can still show a fee number from before the send, so confirm which wallet still holds the NFT before you treat that number as money you can pull.
If you send your v2 UNI/USDC LP token to another wallet, do already-folded swap fees stay with the first address, or travel with the pool token?
They travel with the pool token. Your v2 UNI/USDC LP token is a fungible ERC-20 share of that pair. Swap fees on v2 were already added into the two reserves, so the share you send includes those folded fees. A send is an ordinary token transfer, and the first wallet skips keeping a leftover fee claim after the LP token leaves. The new address holds the same share of that pair. Your old-address screenshot will skip showing the pool token, and will skip showing a separate fee token waiting there either.
Can I create another UNI and USDT pool if one already exists?
On v2, one pair contract is the venue for that token pairing. On v3, the same two tokens can have more than one pool because fee tiers are separate venues, so 0.05 percent and 0.30 percent are different pools. Creating another pair at a new fee is allowed, and it leaves liquidity in the first pool where it was. Check which pool a router picked. A second pool with dust reserves can still quote a wild ratio.
If you already matched both token addresses to contracts you trust, can a router still fill against a brand-new thin fee-tier pool of that same pair instead of the deeper 0.30 percent pool?
Matching UNI and USDC to contracts you already trust names the two tokens. On v3 those same tokens can have a 0.05 percent pool and a 0.30 percent pool as separate contracts. A router can hop through a newly created thin fee-tier even when a deeper 0.30 percent pool of those same tokens exists, so trusted addresses leave you unpinned from the deep pool. If the quote's route shows a thin 0.05 percent hop, that is a different pool.
If a v3 position is out of range, can I still withdraw both tokens?
You withdraw whatever that position currently holds, which may be almost all of one token and almost none of the other. Out of range means that position is no longer earning fees and is no longer the inventory swaps pull from, while the NFT stays transferable. Collect any uncollected fees first if the interface offers that step, then decrease or burn the position. Expect a mix that followed the band if price moved the whole way through your band.
If I send only USDC into a v2 pair as an LP, will the pool accept it?
v2 expects both sides in proportion to the current reserves, so a one-sided deposit is a different action from minting a full share. The first seeder still has to put in both tokens, and later LPs match the ratio already sitting there. If you only have USDC, you are a trader buying the other side, or you are on a v3-style range that can be single-sided at the edge, which is a different claim. Treat a v2 add-liquidity screen as a two-sided deposit.
Researched and written by the BloFin Academy editorial team with AI-assisted drafting. Updated September 2026. Primary sources include Uniswap Labs' liquidity pool support article, Uniswap Developers fees and v2 pool docs, and Tally proposal 100. All facts independently verified against cited documentation current as of September 2026.
This article is educational and general in nature, not financial or investment advice. Cryptocurrencies like UNI carry real risks, including price volatility, venue risk, smart-contract exploits in ecosystem apps, and the chance of losing funds in a pool or on a fake token. Nothing here is a recommendation to buy, sell, hold, or participate in any project. Do your own research, and consider speaking with a licensed professional before making financial decisions. BloFin does not provide investment advice.