The maximum lot size per trade for most pairs is 50 lots* – the equivalent of 5,000,000 units of the base currency. The max lot size for Crude Oil (XTI/USD), Brent (XBR/USD) and Natural Gas (XNG/USD) is 20 lots.
There are no limitations on the number of open trades, regardless the lot size traded.
* If you require a larger maximum trade size, please contact us at support@tier1fx.com