GMX

GMX began in 2021 on Arbitrum as the successor to Gambit, a BNB Chain exchange by the same pseudonymous team. Its first design, now called V1, put every asset into one shared basket, GLP, which took the other side of all trades. V2 ("Synthetics") split that into isolated GM pools, one per market, and GLV vaults that route liquidity across several GM pools of the same backing asset.

There is no order book. You submit an order, a keeper executes it at the Chainlink Data Streams price, and the pool is your counterparty. Liquidity providers earn 63% of fees but also pay out when traders win, which is the part newcomers miss: an LP in GMX is short trader skill.

Markets now include commodities, index products such as SPY and QQQ, and a SpaceX perp, each with its own session-based leverage and fee settings.

On 9 July 2025 an attacker used a reentrancy flaw in V1's `executeDecreaseOrder` path. Re-entering the contract let them open shorts without updating the global average short price, which inflated GLP's calculated value; they then redeemed GLP at that inflated price and withdrew about $42M of the ~$46M in Arbitrum GLP. The vulnerable code had been introduced in 2022 as a fix for another bug and was never audited.

GMX offered a 10% white-hat bounty on-chain within about an hour. The attacker returned roughly 9,000 ETH and 10.5M FRAX within 48 hours and kept about $5M. V2, its pools and the GMX token were not affected.

Under the plan, a holder of $10,000 of GLP would claim about $9,150 of GLV, split between the ETH and BTC vaults, and withdraw the remaining ~$850 from GLP. Claiming required signing a release of further claims against the DAO. Protocols that wrapped GLP, such as Beefy, handled their own users separately.

This was the second time GLP paid for a pricing weakness. In September 2022 a trader manipulated AVAX on V1 using stale-price arbitrage and took about $565K from the pool.

Opening or closing a position costs 0.04% if your trade shrinks the gap between long and short open interest and 0.06% if it widens it. Commodities and index markets have their own schedules, cheaper during market hours (GMX docs).

• Price impact: charged or rebated depending on how your trade moves pool balance. The single-token BTC and ETH pools have it set to zero.
• Borrowing fee: paid every hour a position is open; on anything held for days this outweighs the entry fee.
• Funding: paid from the larger side to the smaller side.
• Swaps: 0.05% or 0.07%; stablecoin pairs from 0.005%.
• Network/execution fee: a small amount of the chain's gas token for the keeper.

The old promise of "zero price impact" belonged to V1. On V2 most markets charge price impact, so large orders do pay for size, just through a published formula rather than a book.

Crypto markets on GMX V2, ETH included, go up to 100x. Other markets are capped lower and some change with trading sessions:

At 100x a 1% adverse move plus fees wipes the collateral, and on commodity markets the liquidation threshold tightens automatically when the session closes, so a position that was safe on Friday afternoon can be closer to liquidation that evening.