Nissan shares slid, heading for a two-day drop of 13%, on concern that the terms of the carmaker’s planned deal with Honda would give investors a lower stake in the proposed joint holding company.

The stock fell as much as 6.7% on Monday in Tokyo. After initially soaring more than 60% since Dec. 17, a day before news of the deal broke, the stock tumbled on Friday as investor focus turned to the starting ratio for a Honda-Nissan tie-up. Shares were also vulnerable to profit-taking on the last trading session of the year.

The ailing Japanese automaker aims to establish and list a joint holding company with Honda in August 2026, according to a Dec. 23 announcement. The exact terms of the arrangement are yet to be decided, but the share transfer ratio will take into account the carmakers’ stock prices, according to the companies. A Nikkei report on Friday estimated the Honda-Nissan share ratio at 5:1.