THE DOLLAR CRISIS : U.S. Currency Back on a Downward Spiral : Markets: The greenback falls against the yen, pound and Swiss franc despite renewed government efforts to prop it up.

Despite the Clinton Administration’s renewed effort to bolster the sagging dollar, the U.S. currency resumed its downward spiral Thursday, falling against the Japanese yen, the British pound and the Swiss franc and edging up only slightly against the German mark.

With his options limited, and timing considered crucial, Treasury Secretary Robert E. Rubin declared, “This Administration believes a strong dollar is in America’s national interest.”

In the measured language of international finance, this kind of statement is considered powerful, and it represented the most forceful defense the Administration has offered since Rubin issued a similar statement when the tumble began late last week.

But it appeared to have no impact on the course of the dollar, which fell once again after rallying Wednesday and early Thursday. By the end of trading Thursday, one dollar was equal to 90.50 yen, down from 91.33 the day before. It was also valued at 1.3945 marks, up slightly from 1.3935 on Wednesday.

“The statement does not seem strong enough to give the market a new direction,” said Olin Wethington, a former assistant secretary of the Treasury for international affairs. “I think the elements that have been moving the dollar are likely to continue pushing it down, despite the statement. Talk doesn’t usually provide much relief.”

He predicted that the value of the dollar “may be getting close to the bottom now.” But, he added, “my guess is we’ll see some volatility for some time.”

Although the Administration’s expression of support for a strong dollar produced only mixed results, it was viewed as significant by some economists. Suspicions have run strong in international currency markets that the Administration quietly favors a weaker dollar, which lowers the cost of U.S. goods sold in foreign countries and can thus improve the U.S. trade balance and boost export-related jobs in this country.

Rubin also held out the possibility that the United States might yet intervene in currency markets to prop up the dollar, saying, “Our policy is to intervene when it makes sense and not to do so when it doesn’t.”

Such a warning, said Lynn Reaser, chief economist at First Interstate Bancorp in Los Angeles, should be read as a strong signal to currency speculators that they could experience sudden shifts in the market--in effect an attempt to talk them out of undervaluing the dollar.

Such intervention late last week proved inadequate, however, and the other dollar medicine--an interest rate increase designed to attract investments to the United States--does not appear to be in the works.

Federal Reserve Board Vice Chairman Alan Blinder said in San Francisco that U.S. economic growth has tapered enough already. His comments suggest that he would not favor an increase in interest rates to cool inflation.

In a speech to the National Newspaper Assn. in Arlington, Va., Rubin said the Treasury has consulted closely with the Fed and with finance ministries of the other Group of Seven nations--Britain, Canada, France, Germany, Italy and Japan, the world’s largest industrial democracies.

Reinforcing his defense of the dollar, he said, “This Administration, from its beginning, has been and remains fully committed to the sound monetary and fiscal policies necessary for sustained growth, low inflation, a strong and stable dollar and maintenance of the dollar as the world’s principal reserve currency.”

A decade ago, the dollar made up roughly 80% of central bank currency reserves. Today such reserves contain more yen and marks, among other currencies, and the dollar share has been reduced to no more than about 50%. This means that a decline in the dollar’s value, though damaging to the United States, hurts others less because their percentages of dollar holdings have been decreased.

But the Administration’s limited approach, known as “jawboning,” can only accomplish so much when the underlying factors that have driven the dollar down remain unchanged and when the talk is not followed up by specific and powerful action, said economists and others with long experience in the fast-paced realm of international currency markets.

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Winners and Losers

A weak or falling dollar creates a number of winners and losers. Among them:

WINNERS * American exporters. A falling dollar can automatically lower prices of American goods abroad, which could strengthen demand for U.S. exports and create jobs.

* American firms operating in Germany and Japan. The surge in the yen and mark, in particular, means U.S. companies earning profits in those currencies receive more dollars when they bring money home.

* U.S. investors in German and Japanese securities. Investments denominated in marks and yen are worth more as the value of the currencies rises, although those gains can be offset if the securities’ prices slide.

* Certain commodity markets. Because the falling dollar threatens to boost prices on goods imported into the United States, gold and other inflation hedges may continue to rise if the dollar falls further.

* Shareholders of U.S. firms viewed as takeover targets. The cheap dollar is likely to boost the number of foreign takeovers of U.S. companies, whose share prices become less expensive when translated into stronger currencies.

LOSERS * American consumers and tourists. A weak dollar can automatically raise prices on imported goods--from Japanese televisions to German cars to French wine. Foreign price hikes could also encourage domestic companies to raise prices. And any American traveling to Europe or Asia will pay much more for hotels, goods and services.

* Japanese and German exporters. They will either have to raise prices on the goods they export to the United States or accept increasingly thin profit margins. The same will be true of companies in other countries with stronger currencies than the dollar.

* The U.S. economy--if interest rates rise. If the dollar’s weakness forces the Federal Reserve Board to boost interest rates in defense of the currency, economic growth could slow much more sharply than the Fed would now like.

* Smaller European and Asian nations. Like the dollar, the currencies of many smaller countries are falling against the mark and yen, raising the price of German and Japanese imports and increasing the threat of higher local interest rates.