Buying power represents the amount a user has in his/her account that is available to trade. It is an aggregation across different currencies and is calculated using the latest exchange rates.
Your buying power amount will be different for each market as it is based on the currency the asset is traded in. See below for an illustration of how this works:
Buying power for US securities
USD settled balance + USD unsettled balance + SGD settled balance
Buying power for Singapore securities
SGD settled balance + SGD unsettled balance + USD settled balance
If you have,
SGD settled balance = S$7,000
SGD unsettled balance = S$3,000
USD settled balance = US$10,000
USD unsettled balance = US$4,000
Given the following conversion rates,
US$1 = S$1.40
S$1 = US$0.70
Buying power for US assets = US$10,000 + US$4,000 + (US$7,000 * 0.70) = US$18,900
Buying power for Singapore assets = S$7,000 + S$3,000 + (S$10,000 * 1.40) = US$24,000
What is settled and unsettled balance?
Settled balance is the available amount that can be withdrawn to your bank account.
Unsettled balance is the amount that cannot be withdrawn to your bank account. This includes any unsettled trade value from sell trades (there is a 2-business day settlement period after a sell trade before the sale is considered final) and any cash rewards from promotions.