(Bloomberg News) BlackRock Inc. Chief Executive Officer Laurence D. Fink, head of the world's largest asset manager, said he understands the concerns of protesters speaking out against financial firms in New York and other cities.

"The protesting is a statement the future is very clouded for a lot of people," Fink, 58, said yesterday during an event in Toronto. "These are not lazy people sitting around looking for something to do. We have people losing hope and they're going into the street, whether it's justified or not."

New York City police have arrested at least 700 people since the rallies began Sept. 17. Demonstrators used social media to spread the protests to cities including Boston, Chicago, Denver, San Francisco, Pittsburgh and Seattle. Those drawn to the "Occupy Wall Street" campaign have used signs and chants to denounce banks and corporate influence on politics.

"People are afraid of the future," Fink said. "We have some structural issues we have to fix."

Labor organizations including Transport Workers Union Local 100, the Metropolitan Transportation Authority's biggest union, marched alongside protesters in New York yesterday. The crowd was estimated at 10,000, said Patrick Brunner, a spokesman for Occupy Wall Street.

Demonstrators initially struggled to build momentum, drawing a fraction of the 20,000 participants that organizers such as Adbusters, a group promoting the demonstrations, aimed to lure to lower Manhattan. Instead, about 1,000 people showed up, and by the time traders and bankers returned to work two days later, the crowd had dwindled to about 200. The number of protesters camping in Zuccotti Park a few blocks from the New York Stock Exchange fell into the dozens that week.

On Sept. 24, a larger group of weekend protesters watched as a New York Police Department deputy inspector used pepper spray on some participants. The incident stoked public interest.