In: Finance
| 
 Date  | 
 Settlement price ($/€)  | 
 Gain/Loss  | 
 Balance  | 
| 
 10/25/18  | 
 1.24  | 
 -----------  | 
 $6,250  | 
| 
 10/26/18  | 
 1.25  | 
 
  | 
 
  | 
| 
 10/29/18  | 
 1.27  | 
 
  | 
 
  | 
| 
 10/30/18  | 
 1.22  | 
 
  | 
 
  | 
| 
 10/31/18  | 
 1.23  | 
 
  | 
 
  | 
a). SInce the futures contract is bought, an increase in settlement price will lead to gain and decrease will lead to loss.
10/26/2018: Change in price = 1.25 - 1.24 = $0.01/€, so gain = 0.01*125,000 = $1,250
Balance = previous day's balance + today's gain/loss = 6,250 + 1,250 = $7,500
10/29/2018: Change in price = 1.27 -1.25 = $0.02/€, so gain = 0.02*125,000 = $2,500
Balance = 7,500 + 2,500 = $10,000
10/30/2018: Change in price = 1.22 - 1.27 = -$0.05/€, so loss = -0.05*125,000 = -$6,250
Balance = 10,000 -6,250 = $3,750
Here, balance falls below the maintenance level of $4,000 so performance bond is called and amount is deposited so that balance again becomes $6,250.
10/31/2018: Change in price = 1.23 - 1.22 = $0.01/€ so gain = 0.01*125,000 = $1,250
Balance = 1,250 + 6,250 = $7,500

Formulas:

b). The futures contract can be closed on 10/31 by selling 1 contract, so on 10/31, change in price is 0.01 and loss is 0.01*125,000 = 1,250 (loss as contract is sold), so balance on Oct 31 becomes 6,250 -1,250 = 5,000
Loss on the contract = 5,000 - performance bond = 5,000 - 6,250 = 1,250 loss