''We're very disappointed,'' said John Levinson, an analyst with Goldman Sachs, who arrived with a colleague, Judy Comeau, too late to see the sculpture. ''It's a tragedy that artists aren't allowed to express themselves in the spirit of Christmas and friendship.''

Mr. Di Modica, who was born in Sicily, created the black-patina bull of bronze and stainless steel in his studio at 54 Crosby Street over the last two years in response to the market crash in 1987. ''He wanted to encourage everybody to realize America's power,'' said Kim Stippa, his assistant.

The Library of Congress said the earliest known reference to bulls and bears as market symbols was in a 1714 book, ''Country Lasses'' by C. Johnson. ''You deal in bears and bulls,'' the author wrote.

On Thursday night, Mr. Di Modica and some friends loaded the bull on a flatbed truck, drove to the deserted financial district and set down the work on the yellow center line of Broad Street, outside the exchange, facing Wall Street.

Daylight brought crowds, and hundreds stopped to admire and analyze the bull, which was charging under the branches of a 60-foot Christmas tree, also set in the middle of Broad Street. Mr. Di Modica handed out copies of ''The Bull,'' a paean-in-a-flier to his work. The Law Steps In