Assume my firm is based in USD and agrees with some counterparty to buy, at time $T$, some quantity $Q$ of asset $A$ for a fixed price $K$.
Assume also that $A$ prices and $K$ are denominated in EUR.
Assume also that we have forward prices:
- For $A$, denotated by $F^A(t,T)$
- For the FX rate, denotated by $F^{FX}(t,T)$, expressed in USD per EUR.
Now my mark-to-market at time $t$ for this agreement is:
$$\text{MTM}_t = DF(t,T)\cdot Q\cdot( F^A(t,T) - K ) \cdot F^{FX}(t,T)$$
I would like to hedge my position for both FX and market effects, assuming I can get perfectly matching contracts for asset and FX in order to hedge.
I would sell $Q$ "lots" of to $F^A(t,T)$ hedge the dynamics of the hedge.
However, I'm unclear how much to hedge for the FX. Indeed, my FX exposure at time $t$ is $F^A(t,T) - K$, which can vary very much from $F^A(t-1,T) - K$ and hence results in an hedge completely off. So, what should be the amount to hedge in FX? I thought about $\mathbb{E}[ F^A(t,T) - K | \mathcal{F_{t-1}}]$ but my backtest doesn't give me good results at all.
Is there a common way of hedging this king of "spread" exposure?