He sold a stake in Barclays Center, the arena that opened in Brooklyn last fall.
He sold a controlling position in the Nets basketball team, which makes its home there. And he recently took on a partner for the residential building now under construction next door.
Now, the developer Bruce C. Ratner, executive chairman of Forest City Ratner Companies, is looking for an investor to buy up to 80 percent of the rest of the $5 billion Atlantic Yards development in Brooklyn, which is to eventually include 14 residential buildings and 6,000 apartments near Atlantic and Flatbush Avenues. The company also has the right to erect an office building that could include a hotel.
Real estate analysts speculate that Mr. Ratner’s company could reap as much as $800 million from the sale of 50 to 80 percent of the remaining project.
The company said that it will remain in control and continue to develop the property, and that the proceeds would help get some buildings, long-delayed, off the ground.
“The money will be invested in the Atlantic Yards project,” said MaryAnne Gilmartin, chief executive of Forest City Ratner. “We’ll retain our position as the managing member. It’s exciting; it raises the possibility that we’ll be able to accelerate vertical development there.”