Japan’s Toshiba Corp. said Wednesday that it received a proposal for acquisition from private-equity firm CVC Capital Partners , in a deal that could be valued at more than $20 billion if completed.

Toshiba said it would seek further details about the offer and consider the proposal carefully.

Toshiba’s shares rose 18% in Tokyo trading Wednesday to close at ¥4,530, equivalent to $41.26, the highest level since December 2016. That gives the company a market capitalization of nearly $19 billion. The Nikkei newspaper said CVC was offering a 30% premium, suggesting the proposal would value Toshiba at slightly more than $20 billion.

CVC declined to comment.

The deal would be one of the largest leveraged buyouts in history, according to Dealogic, and possibly the largest in Asia, rivaling the 2018 deal led by Bain Capital to acquire Toshiba’s flash-memory unit. In a leveraged buyout, a financial company such as CVC uses borrowed money to buy a business, typically hoping to improve its operations and sell at a profit later.