The U.S. dollar yesterday dropped to a new record low against the West German Deutschmark and set the stage for a plunge today below the 2-mark level for the first time ever in foreign exchange trading.

A drop through the psychologically significant 2-mark level could set off further negative reverberations, foreign exchange dealers said, pointing to the "already very depressed" attitude that currency market participants have toward the dollar. The latest drop in the index of leading economic indicators on top of a sharp rise in January consumer prices were cited among the many reasons for its weakness.

Trading yesterday was thin and nervous, with little evidence of foreign or U.S. central bank intervention to bolster the currency. Some concern was voiced that the Federal Reserve Bank is near to exhausting its $4 billion currency swap line with the West German Bundesbank that it has been using to defend the dollar through market intervention.

The Bundesbank released figures yesterday which showed that its currency reserves rose about 2.1 billion marks or more than $1 billion in the week ended last Thursday. Market observers interpreted the figures to mean that two-thirds to three-quarters of the $4 billion swap line has been used up, since a large part of this reserve increase represented drawings of the U.S. Fed on this credit line.

The U.S. currency yesterday gave up most of the gains it has achieved against the mark and the Swiss franc since last Friday after Switzerland's monetary authorities moved decisively to curb capital inflows into their country.

The dollar traded as low as 2.0120 marks in New York, closing at 2.0132 marks, below its record European end-of-the-day low of 2.0175 set yesterday in London. The dollar had closed Monday in New York at 2.0466 marks.

Against the Swiss franc, the dollar closed at 1.8224 in New York compared with 1.8775 the day before. The record intra-day low against the Swiss franc was set last Thursday when the dollar traded at 1.7880 before Switzerland announced several measures to halt foreign purchases of Swiss francs. The renewed decline of the dollar against the Swiss franc despite the measures underlined the U.S. currency's basic downtrend.

In Zurich, however, stock prices were slashed anywhere from 5 to 10 percent in one of the most severe setbacks ever suffered on that exchange. Dealers said buyers were hard to find because of the ban on foreign purchases which became effective yesterday. Swiss bond prices were also battered.

A top Swiss central bank official was dispatched to the U.S. for consultations on what measures this country might take to strengthen its currency.

Against the Japanese yen, the dollar declined only slightly, closing in New York at 238.15 yen to the dollar, down from 239.06 the day before.

One concern overhanging the exchange markets, dearlers said, was the Friday's release of the U.S. January trade deficit figure, which some have estimated to be as high as $2.5 billion. There is worry that heavier oil imports as a result of the coal strike could make for a larger deficit and a still weaker dollar.