Same as you, of course
Kim buys $10,000,000 notional value of protection using the CDX contract. Kim’s view turns out to be correct and after 12 months the CDS spread on the HY CDX contract has doubled and the contract’s spread duration is 3.77.
The fund is buying protection and therefore needs to pay the fixed coupon of 0.05 × $10,000,000 = $500,000.
|Initial CDS Price|= 1 + [(Fixed coupon – CDS spread) × Spread duration]|
||= 1 + [(0.05 – 0.035) × 4.66]|
||= 1.0699|
The CDS price after 12 months when the CDS spread has doubled to 700 bps and the spread duration has fallen to 3.77 is calculated as:
|CDS price in 12 months|= 1 + [(0.05 – 0.07) × 3.77]|
||= 0.9246|
Because the fund has bought protection, it is a short credit risk, and profits as CDS prices fall. Hence, the profit/loss from changes in the CDS price = (1.0699 – 0.9246) × $10,000,000 = $1,453,000.
Total return, including the coupon outflow = $1,453,000 − $500,000 = $953,000.
However, when I see these questions, I always tend to go first for the long-short method, i.e. applying the formula to calculate the value of the long-short position:(-change in spread ) x effspreaddur x notional.
Is there any way to know when it is better to calculate the change in price, versus the value of the long/short position? Do they specifically need to say smth about long-short, or specifically state, that, for instance, spreads on 5y decrease, while the ones on 10y increase?
Otherwise, you should rather go for computing the changes in price?