Mark Thompson resigned as CIO of London CIV due to personal reasons, a spokeswoman said. It is effective immediately.
Mr. Thompson joined London CIV at the start of September. Mr. Thompson replaced Michael Pratten, who has been acting as interim CIO.
The £19 billion ($23.7 billion) London CIV, a pool of 32 local government pension schemes, will focus on finding both an interim and permanent CIO following Mr. Thompson's departure, the spokeswoman said.
"I am not ready for a return to a full-time and demanding role and I cannot therefore commit fully to the London CIV," Mr. Thompson said in a news release. "I currently intend to follow a path away from a full-time executive role to spend more time with my family. In no way is this a reflection of London CIV and its objectives. In my short time at the London CIV, I have been impressed by the talented and hardworking individuals, who share a common goal of meeting the company's objectives for its clients."
CEO Mike O'Donnell said in the news release that he was "sad that Mark had decided to resign but understands his reasons for doing so."