Broadcom Ltd. and a group led by KKR & Co. are emerging as the two leading bidders for Toshiba's semiconductor unit, while South Korea's chipmaker SK hynix and Bain Capital have also joined the final bidding, as of Friday's deadline for second-round offers.

According to Bloomberg's sources, Broadcom is offering about 2.2 trillion yen ($20 billion) and would face simpler regulatory reviews than some rivals.

The competing group, which includes state-backed Innovation Network Corp. of Japan and Development Bank of Japan, plans to offer about 1.8 trillion yen and would benefit from support from the country's government.

U.S. buyout firm Bain Capital LP plans to bid around 1.5 trillion yen ($13.5 billion), according to Reuters. The bid will be made in partnership with South Korea's SK Hynix but the chip maker will not take a leading role due to anti-trust concerns.

Toshiba's partner Western Digital, which jointly runs Toshiba's main semiconductor plant and is one of the suitors for the chip unit, is seeking to block any sale that does not have its consent. Western Digital is presumed to have been excluded in the second bidding.

Other major tech firms, such as Taiwan-based Hon Hai better known as Foxconn, are also expected to join the bidding.

The Japanese TVs-to-nuclear conglomerate plans to close a second-round of bidding for the world's second-largest NAND chip manufacturer on Friday but much of the sale is uncertain. But the company is also open to entertaining new bids after the second round closes, according to some unconfirmed sources.

Toshiba is depending on the sale to cover a $9 billion hole in its accounts due to problems at now bankrupt unit Westinghouse.