Leaf Group (LEAF) rose 4.9% after a group of stockholders, who beneficially own about 25% of LEAF shares outstanding, said that the company's planned sale to Graham Holdings (GHC) for $8.50/share is "grossly inadequate."The group, which consists of VIEX Capital Advisors, Osmium Partners and Oak Investment Partners, said it believes a conservative sum-of-the-parts value of the stock is $17.43/share, according to a statement.The shareholders argue that the "shotgun style wedding" sale was process was less than seven weeks and was "deeply flawed." The holders plan to carefully review the company's proxy materials before deciding on how they plan to vote.The shareholder groups' comments come after holder Boyle Capital yesterday said that the Graham proposed deal "materially" undervalues Leaf. LEAF now trading at $9.02, a 6% premium to the $8.50/share price.Recall April 5, Graham Holdings to acquire Leaf Group for $8.50/share or $323m.