A judge in Manhattan has dismissed a lawsuit brought by the financier Alphonse Fletcher Jr. against the Dakota building, ruling that Mr. Fletcher had failed to provide evidence that the celebrated building’s co-op board had discriminated against him because he is black.

The ruling was the latest in a series of reversals for Mr. Fletcher, a former Wall Street wunderkind who rose to become a prominent hedge fund manager and philanthropist but who has struggled in recent years, seeing one of his funds forced into bankruptcy and tax liens placed against some of his properties.

That fall from grace began in 2011, when Mr. Fletcher sued the Dakota’s co-op board, which he had once led, after it refused to let him buy an apartment adjacent to his fifth-floor home. He accused the board of discriminating against him and other black and Hispanic residents, including the singer Roberta Flack.

The suit touched off one of the ugliest co-op battles in the history of Manhattan real estate. The board members — many of them powerful business leaders in their own right — fought back, saying in depositions that they had rejected Mr. Fletcher because he had only $50,000 in liquid assets, millions in debt and mounting losses at his businesses.