Fidelity Investments, the world's fourth-largest mutual fund company, has cut the valuation of its stake in Chinese fintech giant Ant Group by half, according to a regulatory filing, The Wall Street Journal reported Monday.

Fidelity's latest valuation of Ant Group was $144 billion as of the end of February, the report said. The valuation came at a time when Ant Group was under a crackdown by Chinese regulators.

Ant Group declined to comment on it. And Fidelity did not immediately respond to the reporter's request for comment.

The investment firm is said to have valued the fintech giant at $295 billion as of the end of August last year. Fidelity, meanwhile, was one of a small group of global investors that took a stake in Ant Group three years ago.