Transaction sizes
If we take 10,000 units of base currency, the minimum transaction size, offered by FXOpen broker, amounts to 0.1 lot with an incremental lot of 0.01. The term “fractional” pip is typical of the ECN model of trading. 1 fractional pip with 0.1 lot of trading volume is approximately equal to $0.1.
The maximum transaction size for ECN accounts depends on the available liquidity i.e., a certain number of buyers and sellers ready to become counterparties for your order at current prices. The deal will be executed provided the available liquidity on a certain currency pair is sufficient to complete a trade. In periods of low liquidity, however, an order may be executed only partially.