Files with the MQ4 extension are used by the trading platform for investing in the Forex, Futures and CFD markets called MetaTradaer. MQ4 files are used to store indicators to help you make investment decisions, as well as scripts, libraries, and comments. Such a file contains code written in a special programming language MetaQuotes Language 4 specially developed for MetaTrader.

MQ4 are files specific to MetaTrader version 4. MetaTrader 5 gives files of this type the MQ5 extension.