The dollar-yen exchange rate could remain on a roller-coaster ride through much of the year ahead.

The currency market remains locked in a crosscurrent between fears of the dollar’s fall below 100 yen and speculation over dollar-selling intervention by the Bank of Japan.

At the outset of the year’s first trading session Tuesday in Tokyo, Japanese export-oriented companies unloaded their dollar holdings, making up for lost time during the yearend and New Year holiday season.

Their stepped-up sales sent the dollar falling below 101.50 yen in early morning trading, prompting the BOJ to step in once again.

Although repeated intervention by the BOJ has helped ease fears of the yen’s further appreciation at least temporarily, given the excess supply of dollars, the greenback could soon come under renewed selling pressure.

It remains to be seen whether the BOJ is determined to prevent the dollar from falling below 100 yen at any cost in the near term.

Intervention to stabilize the dollar above this level could cost the BOJ somewhere between 10 billion yen and 15 billion yen.

With worries about the Year 2000 computer problem out of the way, investors appear ready to unwind U.S. securities portfolios they have built to hedge assets against losses in recent months.

It is now widely anticipated that the Fed’s policy-setting Federal Open Market Committee will tilt its policy toward credit-tightening when it meets early next month.

The Federal Reserve refrained from tightening its grip on credit amid uncertainty about the Y2K problem.

Fears of higher interest rates are weighing on the dollar’s value.

Against a backdrop of brightening economic prospects in Germany, France and other European nations, the euro has recouped much of its losses against the dollar, raising speculation that the single European currency has bottomed out close to one-to-one parity with the dollar.

The market is now trying to assess whether an agreement for policy coordination will emerge at the meeting of finance officials from the Group of Seven industrial nations, set for Jan. 22 in Tokyo.

One false step and the dollar could come under downward pressure against all other key currencies.

The yen’s strong showing has been fueled largely by expectations of economic recovery in Japan and positive effects of the second extra budget approved by the Diet in November.

At the same time, unless the market is convinced that Japan’s ultraeasy money policy will soon end and that economic recovery is gathering momentum, the yen could come under selling pressure against all other key currencies.