Your MT5 account is on a tiered margin system that is used to set the margin rates at levels that reflect the size of your position in a particular market.
This means that there will be different margin requirements at different levels of exposure. Smaller positions generally benefit from better market liquidity, so these positions attract our lowest margin rates.
Our tiers start at one, with the lowest margin rates, and go up to four, with the highest margin rates.
Calculation for Rolling Indices: Open price * contract size * volume in lots * margin rate as a decimal = margin required
A client buys 800 lots of US500Roll at a price of USD 4,201. For the first 500 lots the margin rate is 0.20% (1:500).
Margin requirement = 4,201 (open price) * 1 (contract size) * 500 (volume in lots) * 0.2%
(margin rate) = USD 4,201.
For the remaining 300 lots the margin rate is 0.5% (1:200).
Margin requirement = 4,201 (open price) * 1 (contract size) * 300 (volume in lots) * 0.5%
(margin rate) = USD 6,301.50.
The same client now buys another 100 contracts of US500Roll at a price
of USD 4,300.
The total exposure on US500Roll is now 1,800 lots which in margin tier 2 is at 1.0% margin
Margin requirement on the new position = 4,300 (open price) * 1 (contract size) * 100
(volume in lots) * 0.5% (margin rate) = USD 2,150.
The TOTAL margin required becomes USD 10502.50 + USD 2,150 = USD 12,652.50