The central and Tokyo governments are seeking a ¥700 billion ($4.7 billion) valuation for Tokyo Metro as they prepare to list the subway operator as early as the end of October, three sources said, in what would be the nation's biggest initial public offering (IPO) in roughly six years.

The two governments, which own 100% of Tokyo Metro, plan to arrange a meeting of brokerages within a week for a briefing on the IPO and expect to receive approval for the listing from the Tokyo Stock Exchange as soon as mid-September, the sources said.

With half the company to be sold, the IPO could raise ¥350 billion at that valuation, which would exceed the size of Kokusai Electric's IPO last year and become the largest since SoftBank Group listed its wireless unit in 2018.