(FORTUNE Magazine) – Economists have a hard enough time deciphering the world economy without having to worry about money that just plain disappears. But in the past several years a black hole seemingly has swallowed hundreds of billions of dollars passing between nations. Without accurate data, economists can't analyze trade policies and companies have a hard time forecasting currency values. Now, after two years of study, the International Monetary Fund thinks it can explain some of the missing money. The net value of each country's transactions with other countries in goods, services, investment income, and gifts is its current account balance, either a deficit or a surplus. Because one country's deficit must be another's surplus, all countries' accounts together should total zero. Since the late Seventies, however, the numbers reported to the IMF have instead added up to a huge deficit -- as much as $114 billion in 1982 (see chart). Countries were either overstating how much they paid or understating their receipts. The biggest and fastest-growing discrepancy is in reported investment -- about $42 billion of it was missing in 1984. Part of that is surely concealed capital flight from some of the world's less stable nations. Part slips between regulatory cracks. Many countries, including the U.S., do not require citizens to report foreign deposits or investments, so a government can't always tell when such investment flows in from abroad. The second-largest discrepancy lies in shipping accounts. Many shipping transactions are between companies of different nationalities, and shipping outfits are often a welter of divisions and subsidiaries based around the world. Payments are easily measured when they leave the customer's country, but get lost on their way to the shipper's. The IMF thinks that as much as a third of the world's shipping revenue is not reported by any country.

CHART: NOT AVAILABLE CREDIT: BOB SCOTT SOURCE: INTERNATIONAL MONETARY FUND CAPTION: A culprit: funds fleeing to stability DESCRIPTION: Current account discrepancy, 1978-1985. Color illustration: leaking money bag.