The contract for pairs must technically be filled 5pm on the second day. What happens if I am working on a medium term strategy that may take several weeks? Does the platform broker automatically convert this to a future, what happens and what are the implications for carry trade?
Once your order expires, your broker will close and re-open your trade, so you can keep it open.
For instance, you go long Gbp/Usd at 1.4500, by the end of the day price is at 1.4577. Your broker will close and open your trade again at 1.4577, and will do the same day after day until you actually decide to close it.
The main implications I see are spreads. Everytime your order is closed and re-opened you pay the spread for both operations, but if your trade is positive and moving, that shouln’t be a big issue.
Hope that helps.