The seeming ability of a number of banking organizations to make consistent profits from foreign exchange trading likely derives not from their insight into future rate changes but from making markets and consistently being able to buy at the bid and sell at the offering price, pocketing the spread.
BIS Review 50/2003  1  as a whole necessarily sum to zero, so do net capital flows. Because for any country the change in net claims against all foreigners cumulates to its current account balance (abstracting from valuation adjustments), that balance must also equal the country’s domestic saving less its domestic investment.