In this article, we will take an example to understand margin calculations work.
Assume a long position in 10 futures contracts on XYZ stock. Each contract covers 100 stocks.
The contract price is $10, the initial margin required is $100 and the maintenance margin required is $75.
For 10 contracts, the total initial margin is $1,000 and maintenance margin is $750.
During the next three days, the price changes as follows:
Day 1: -30 cents
Day 2: +10 cent
Day 3: -30 cents
Let's compute the margin balance for each of the five days.
Since there are 100 stocks in each futures contract, a 1 cent change in price changes the contract value by $1 or $10 for 10 contracts.
The following table shows the margin balance for the three days.
| Day | Required Deposit | Price/Stock | Daily Change | Gain/Loss | Balance |
|---|
| | | | | |
| 0 | | | | | |
|
1000
|
10
|
0
|
0
|
1000
|
|
1
|
0
|
9.7
|
-0.3
|
-300
|
700
|
|
2
|
300
|
9.8
|
0.1
|
100
|
1100
|
|
3
|
0
|
9.5
|
-0.3
|
-300
|
800
|
Let’s understand the margin calculation on each day. On Day 1 itself, the margin balance has gone below the maintenance margin of $750. It has reach $700 and the trader is required to deposit $300 to replenish the margin balance back to the original $1000. On day two, the price moved up creating a gain of $100. The margin balance at the end of day two is $1100. On Day 3 again, the price moves down by 30 cents. However, at the end of the day, the margin balance is $800, that is, above the margin balance. So, no margin call is required.
