When you click the trade button on one instrument, system will automatically choose the account that has the same currency with the instrument. For example, if you are trading Apple on Nasdaq, your USD account will be chosen automatically if you have one USD account. If you are about to place a trade in an instrument denominated in a currency, different from the currency of the account while you also do have an account available in the same currency as the instrument you are trading, we display a yellow warning, as this will involve currency conversions. For example, you do have a USD account but you choose the SGD account.The warning is informative only and will not prevent you from placing a trade.
In the image above, the selected instrument is Apple in USD., but the account is in SGD.
If you decide to buy Apple stocks from your SGD account, the system converts the necessary amount of SGD to USD to purchase the stock. Please, be aware, that a currency conversion fee applies in such cases.
What happens if you trade USD stocks from your USD account, but the account lacks sufficient funds, while your other accounts, such as your SGD account, have sufficient funds? Read Trading with Insufficient Funds in a Sub Account
Read more:
Currency conversion
Open a sub account in a different currency