MT4 (MetaTrader 4)
Definition
MT4 is MetaTrader 4 — MetaQuotes' retail forex trading platform launched in 2005. Despite being superseded by MT5 since 2010, MT4 remains the most-widely-deployed retail forex platform in 2026 because of its enormous installed EA library and broker support. Strategies and EAs written for MT4 require porting to run on MT5.
In-depth: MT4 (MetaTrader 4)
MT4 occupies an unusual position in the 2026 forex ecosystem: technically obsolete since MT5 launched in 2010, but practically dominant because of network effects in the retail forex market. The installed base of MT4-compatible EAs, the depth of broker support, and the simpler programming language combine to give MT4 sustained relevance.
Key MT4 characteristics:
• **MQL4 programming language**: simpler than MQL5, procedural rather than object-oriented, with a flatter learning curve for non-programmers. Most retail-developed EAs were written for MT4 first • **Single-tick processing model**: MT4 processes ticks one at a time, which is adequate for most strategies but limits high-frequency trading • **32-bit architecture**: MT4 is 32-bit only, which limits memory and modern CPU feature utilisation • **Single-instrument backtest**: MT4 Strategy Tester runs one symbol at a time, limiting multi-pair strategy validation • **Broker support**: virtually every retail forex broker supports MT4 alongside MT5; many smaller brokers support only MT4
MT4 vs MT5 for EA buyers:
• **EA selection**: MT4 has the larger installed library; many older legacy EAs remain MT4-only • **Modern strategy development**: new commercial EAs typically ship both MT4 and MT5 versions; some advanced strategies (multi-instrument, ML-augmented) are MT5-only • **Programming language barrier**: MQL4's simpler syntax has produced more amateur-developed EAs; MQL5 requires more programming sophistication • **Broker condition parity**: same broker accounts typically perform identically across MT4 and MT5 versions; platform choice doesn't materially affect realised performance
For EA buyer evaluation in 2026: MT4 is acceptable for established strategies with proven track records. New strategy purchases should prefer MT5 versions when available because MetaQuotes' development focus has been on MT5 for years and MT4 support windows are narrowing. Buyers committed to MT4-only EAs should budget for eventual migration cost when broker support inevitably ends.