At the program’s peak, the racial disparities in its enforcement were jarring. Of 575,000 “stop and frisks” conducted in 2009, black and Latino people were nine times as likely as white people to be targeted by the police (even though, once stopped, they were no more likely to actually be arrested). In 2011, police stopped and questioned 684,330 New Yorkers; 87 percent of those stopped were black or Latino.

Mr. Bloomberg, a billionaire who would self-finance his presidential run, acknowledged on Sunday that the program had led to an “erosion of trust” and he hoped to “earn it back.”

“Over time, I’ve come to understand something that I long struggled to admit to myself: I got something important wrong,” he said. “I got something important really wrong. I didn’t understand back then the full impact that stops were having on the black and Latino communities. I was totally focused on saving lives — but as we know: good intentions aren’t good enough.”