MetaTrader 4 (MT4)

MetaTrader 4 (MT4) is the absolute, undisputed, monolithic standard in the global Retail Forex (Foreign Exchange) and CFD (Contract for Difference) industry. Released in 2005, it is notoriously outdated looking, yet it maintains a complete stranglehold on the market because millions of traders absolutely refuse to learn a new system. Its absolute superpower is "Expert Advisors" (EAs). MT4 uses a proprietary coding language called MQL4. This allows retail traders to code incredibly complex Algorithmic Trading Bots that run 24/7. Because MT4 has been around for decades, there is a massive, sprawling global marketplace where traders can buy, sell, and rent thousands of pre-built EAs, indicators, and scripts, creating an unbeatable network effect. From the Brokerage side, MT4 operates as a massive "White Label" engine. A new broker in Cyprus does not build their own trading software. They pay MetaQuotes a massive licensing fee, slap their own logo onto MT4, and instantly offer a world-class trading engine to their clients, completely outsourcing their entire technological infrastructure.