High foreign interest \(\Rightarrow\) backwardation (peso)
So, currency carry trade = sell contango futures and buy backwardation futures
Expensive and cheap futures
Sell contango futures = sell futures when futures price is high (relative to spot)
Buy backwardation futures = buy futures when futures price is low (relative to spot)
So, currency carry trade = sell expensive futures and buy cheap futures (relative to spot)
Appreciation and returns
Consider selling 2-month euro (contango) futures and buying 2-month peso (backwardation) futures at date \(t\) and holding for 2 months, until futures price = spot