banks hedging commod exposure

Banks typically hedge their exposure to large positions, such as being short puts, by taking an opposite position in the market. This could involve buying futures or options contracts that would increase in value if the underlying asset decreases in value. This way, any losses from the short put position would be offset by gains from the hedging position.

However, it's important to note that hedging isn't always perfect and there can still be some residual risk. The effectiveness of a hedge can depend on many factors, including the correlation between the hedging instrument and the underlying asset, the volatility of the market, and the timing of the hedge.

In the case of a bank helping Mexico hedge its oil price exposure, the bank could potentially hedge its position by taking a long position in oil futures or options. If the price of oil falls, the bank would lose money on its short put position but would make money on its long futures or options position, thereby offsetting the loss.

Remember, this is a simplified explanation and the actual hedging strategies used by banks can be much more complex and sophisticated, involving a range of different financial instruments and techniques.

Sources:

1. Argentina Case Study: How a Black Market Currency Emerges
2. HF exits from macro vol desks?
3. Investment bankers are doing God's work
4. Goldman Commodities Profits - What happened?