Blackrock Inc. BLK, +0.86% has ousted Mark Wiseman for failing to disclose a romantic relationship with a client, the Wall Street Journal reported Thursday, citing a person familiar with the matter. Wiseman, who was viewed as a potential successor to Blackrock’s Chief Executive Lawrence Fink, breached the company’s policy by engaging in the relationship, the paper reported. The executive and his wife Marcia Moffat, head of Blackrock’s Canada office, were viewed as a married power couple at the asset manager. The relationship was with another employee. “I engaged in a consensual relationship with one of our colleagues without reporting it,” Mr. Wiseman in a memo Thursday, according to the paper. “I regret my mistake and I accept responsibility for my actions.” Wiseman came to Blackrock in 2016 from the Canada Pension Plan Investment Board. Blackrock shares were up 0.8% Thursday, and have gained 24% in 2019, matching the S&P 500’s SPX, -0.07% gains.