Account Base Currency

The account base currency is the currency a trading account is denominated in: deposits, balance, equity, margin requirements, and every realised profit or loss are expressed in it. Brokers usually offer a choice of account currency at registration — commonly major currencies, sometimes local ones — and switching later is often difficult or impossible. The choice matters for cost, because results realised in another currency must be converted back at the broker's rate, adding a conversion charge to each closed trade, and because margin requirements shift as exchange rates move against the base currency. Matching the base currency to how an account is funded also avoids conversion on deposits and withdrawals.