Indian pharmaceutical firm Sun Pharmaceutical must double its current offer for the remaining stake in Taro if it is to be successful.

Sun currently owns 66% of the company and has offered to acquire the remaining 34% at $24.5 a share, equivalent to a 26% premium over its $19.45 trade price on Monday.

This bid was, however, rejected by one of the remaining shareholders, Grand Slam Asset Management, which has requested almost double that amount.

Grand Slam has stated it believes a fair evaluation would be at least 15 times the company’s EBITDA, corresponding with six similar acquisitions of US generic drug manufacturers, equivalent to $48.5 a share.

Grand Slam reiterated its stance in a letter to the Taro board, which also urged the hire of independent counsel and investment bankers in order to oversee any further Sun offers.