Aptos hides pending trades until their order is fixed

Aptos has switched on an Encrypted Mempool on its mainnet. The feature is optional: users who opt in keep a pending transaction encrypted until the order of transactions in a block has been finalised, which removes the window in which bots read an order and trade around it.

The mechanics are straightforward. A compatible wallet or app encrypts the transaction on the user's device before sending it. The assets, amounts and contract call stay hidden, while the sender's address and the gas fee remain visible. Validators agree on ordering without seeing contents, and only once that order is fixed do they decrypt the transactions together and execute them. No single validator can decrypt a pending transaction on its own.

Aptos says it built the feature for institutions submitting large transactions, traders trying to avoid MEV, AI agents and builders. Its own explanation of the problem is the familiar one: on most chains anyone watching the network sees the function being called, the assets and the amounts before execution, and bots use that to trade against the user or copy the strategy.

Protection is not free. Aptos's developer documentation sets a minimum gas price for encrypted transactions at twice the network's base minimum, and the company reports about 20 milliseconds of added latency per block in tests with 50 nodes, compared with its existing consensus.

The scale of what is being defended against comes from third-party data cited by Cointelegraph: sandwich attacks cost Ethereum traders about $60 million over the 12 months to October 2025 according to EigenPhi data, while Bitquery counted nearly 6.9 million such attacks on Solana over 11 months, affecting about 2.2 million wallets and earning bots $29.7 million.