DEX pools don't have order books. They price algorithmically using a constant-product market maker:
x · y = k
Where x and y are the two tokens in the pool, and k is a constant the pool tries to preserve. To buy y, you deposit x; the pool adjusts y downward to keep k unchanged. Cross-chain DEX-DEX means you do this twice — once on each side of the trade, on two independent chains, with a bridge between them.
Why bigger trades hurt
The curve is nearly flat near the current ratio, so small trades are almost mid-priced. Bigger trades walk the curve and pay progressively worse rates.
Concrete example: a pool holds 100 ETH and 100,000 USDC, so 1 ETH = 1,000 USDC. Buying 1 ETH costs about 1,010 USDC — minimal slippage. Buying 10 ETH at once costs about 11,111 USDC — an effective rate of 1,111 per ETH, 11% slippage in a single trade. Same pool, same starting price, completely different fill.
The mid-price spread you see on a DEX aggregator is not the spread you'll actually capture. A 5% mid-price gap between two pools on different chains can shrink to 1% once you walk both AMM curves at your real size, pay pool fees (typically 0.3% per swap), gas on two chains, the bridge fee, and any price movement during bridge finality. Finder walks both pools at a target notional so the displayed number is what you can realistically execute.
Three bridge types — and why it matters
Not all bridges are equal. Their mechanics directly affect speed, fees, and — most importantly — how much you have to trust the bridge with your money.
The fewer trust assumptions a bridge requires, the safer it is — usually at the cost of being slower.1. Lock & Mint (wrapped tokens). The bridge locks your token in the source chain and mints a wrapped version in the target chain. Portal (formerly the Wormhole token bridge) works this way. The catch: the wrapped token's value rests entirely on the bridge's security — and bridges built on this model have historically been the most-targeted in DeFi hacks.
2. Liquidity Pool bridges. The bridge holds liquidity pools in both chains: you deposit into the source pool and receive from the destination pool. Across, Hop, and Stargate work like this. Stargate runs on LayerZero and uses unified liquidity pools to transfer native assets without wrapping, with a 0.06% protocol fee. Fast and cheap, but at large sizes you pay slippage against the pool's size.
3. Native / CCTP (burn & mint). The most trust-minimal model: the token is burnt in the source chain and re-minted as native on the target chain, no wrapping involved. The reference implementation is Circle's CCTP for USDC. No wrapped-token risk, but finality is longer — a transfer can take 13–19 minutes.
Bridge aggregators — don't pick a bridge manually
The same way you don't pick a single DEX manually, you don't pick a single bridge. Bridge aggregators compare dozens of routes and choose the optimal one for cost, speed, and risk. LI.FI (front-end: Jumper) aggregates dozens of bridges and DEXes into one router. Bungee (rebranded from Socket in early 2026) is embedded in Coinbase Wallet and MetaMask Bridge. deBridge, Squid, and Rango work the same category. They'll bundle swap + bridge + swap into one operation and quote the real final amount on the destination chain — exactly the number you need to compute profit.
