Japan’s s technology and manufacturing giant Toshiba Corp (TYO:6502), its share price surges nearly 6% at 4,860 yen, the highest level since 2015, in the Asian stock market Wednesday.

The surge comes after news that U.S. private equity firm KKR & Co. is exploring a bid for Toshiba Corp.

Toshiba has received a $21 billion offer from CVC Capital Partners. KKR is considering an offer that could exceed the one by CVC.

Canadian investment giant Brookfield Asset Management Inc. is also in the preliminary stages of considering a bid for Toshiba, another person familiar with the matter said.

The people familiar with the matter said these bids are in the early stages of exploration and have not made any final decisions, and may not issue a takeover bid.

Toshiba CEO Nobuaki Kurumatani resigned Wednesday under pressure from shareholders who aims to block the $21 billion takeover offer from CVC.