Robert Stolarik for The New York Times

For months the protesters had planned to descend on Wall Street on a Saturday and occupy parts of it as an expression of anger over a financial system that they say favors the rich and powerful at the expense of ordinary citizens.

As it turned out, the demonstrators found much of their target off limits on Saturday as the city shut down sections of Wall Street near the New York Stock Exchange and Federal Hall well before their arrival.

By 10 a.m., metal barricades manned by police officers ringed the blocks of Wall Street between Broadway and William Street to the east. (In a statement, Paul J. Browne, the Police Department’s chief spokesman said, “A protest area was established on Broad Street at Exchange Street, next to the stock exchange, but protesters elected not to use it.”)

Organizers, promoters and supporters called the day, which had been widely discussed on Twitter and other social media sites, simply September 17. Some referred to it as the United States Day of Rage, an apparent reference to a series of disruptive protests against the Vietnam War held in Chicago in 1969.

The idea, according to some organizers, was to camp out for weeks or even months to replicate the kind, if not the scale, of protests that erupted earlier this year in places as varied as Egypt, Spain and Israel.

Bill Steyert, 68, who lives in Forest Hills, Queens, stood near the barricades at Wall Street and Broadway and shouted, “Shut down Wall Street, 12 noon, you’re all invited,” as tourists gazed quizzically at him.

Talking to a reporter, he elaborated, “You need a scorecard to keep track of all the things that corporations have done that are bad for this country.”

Nearby, Micah Chamberlain, 23, a line cook from Columbus, Ohio, held up a sign reading “End the Oligarchy” and said he had hitchhiked to New York. “There are millions of people in this county without jobs,” he said. “And 1 percent of the people have 99 percent of the money.”

Throughout the afternoon hundreds of demonstrators gathered in parks and plazas in Lower Manhattan. They held teach-ins, engaged in discussion and debate and waved signs with messages like “Democracy Not Corporatization” or “Revoke Corporate Personhood.”

Organizers said the rally was meant to be diverse, and not all of the participants were on the left. Followers of the fringe political candidate Lyndon LaRouche formed a choir near Bowling Green and sang “The Star Spangled Banner” and “The Battle Hymn of the Republic.” Nearby, anarchists carried sleeping bags and tents.

At one point in the early afternoon, dozens of protesters marched around the famous bronze bull on lower Broadway. Among them was Dave Woessner, 31, a student at Harvard Divinity School.

“When you idealize financial markets as salvific you embrace the idea that profit is all that matters,” he said.

A few minutes later about 15 people briefly sat down on a sidewalk on Broadway, leaning against a metal barricade that blocked access to Wall Street. For a moment things grew tense as officers converged and a police chief shoved a newspaper photographer from behind.

After a police lieutenant used a megaphone to tell those sitting on the sidewalk that they were subject to arrest the protesters got up and marched south.

Mr. Browne said no permits had been sought for the demonstration but plans for it “were well known publicly.”

Mr. Browne said two people in bandanna masks were taken into custody for trying to enter a building at Broadway and Liberty Street that houses Bank of America offices. A third person fled.

As a chilly darkness descended, a few hundred people realized one of the day’s objectives by setting foot onto Wall Street after a quick march through winding streets, trailed by police scooters.

At William Street, they were blocked from proceeding toward the stock exchange, and the march ended in front of a Greek Revival building housing Cipriani Wall Street. Patrons on a second-floor balcony peered down.

As some of the patrons laughed and raised drinks, the protesters responded by pointing at them and chanting “pay your share.”