The field of bidders vying to buy Toshiba in what would be Japan’s biggest ever buyout has narrowed to two frontrunners, one consortium led by US private equity group Bain Capital and another spearheaded by a Japanese domestic fund, according to three people familiar with the matter.

The sale of the 146-year-old industrial conglomerate has been subject to an extensive due diligence process in a round of bids that began in the spring and is expected to last through November. A deal for Toshiba could value one of Japan’s best known companies at as much as $22bn.

Private equity group Japan Industrial Partners, which has previously acquired assets from Sony and Olympus, has been given a preferred status in the second round of bidding but has not signed an exclusivity agreement, two of the people said. 

Alongside the groups led by Bain and JIP, US private equity group Brookfield and European buyout firm CVC, whose original $20bn approach for Toshiba in 2021, forced the resignation of its then president and triggered the current bidding war, also made it to the second round.

Toshiba has evolved into a sprawling collection of subsidiaries and non-core assets, some of which have been listed separately, but many of which remain as potential targets for future sell-offs. The due diligence process has provided bidders with vast collections of data and factory access normally off-limits to investors.

The progression of the sale process has given the second-round bidders an unprecedented level of access to one of Japan’s most complex business groups.

JIP is in talks with an array of Japanese companies including Chubu Electric and financial services group Orix, as well as private equity groups, but the members of its consortium and financing details have not yet been finalised, according to those people.

Another person with direct knowledge of the talks questioned whether the consortium led by JIP would be able to offer the most competitive pricing. 

JIP declined to comment. Orix said it was considering an investment in Toshiba but added that no decision has been reached. Chubu Electric said it signed a nondisclosure agreement with Toshiba and another investment fund it declined to name. 

JIP had initially partnered with Japan Investment Corp, an investment fund backed by the Japanese government, in the first round of bidding. But the two have since parted ways, with JIC now in talks with Bain Capital, which had been considered the frontrunner in the bidding battle.

JIC and Bain declined to comment.

In a statement, Toshiba declined to comment on the bidders, saying it could “undermine fair process”.