Four of Japan's top property and casualty insurers and other financial firms plan to sell around ¥500 billion ($3.1 billion) of shares in Honda Motor, three people said, as the unwinding of cross-shareholding practices accelerates.

Tokio Marine Holdings Sompo Holdings and two units of MS&AD Insurance Group will together offload shares in the automaker, said the people, who declined to be identified because the information has not been made public.

Other financial institutions will also pare back their Honda stakes, bringing the total sale to around ¥500 billion based on Honda's current share price, the sources said.