A Chipotle shareholder is suing the fast-casual chain over viral social media complaints about skimpy portion sizes.

Chipotle Mexican Grill was sued on Monday by shareholders for concealing how many of its restaurants were skimping on portions, forcing the chain to spend more on ingredients and hurting its stock price.

Chipotle Mexican Grill (CMG) is facing a class action lawsuit from shareholders who claim the company misled investors about inconsistent portion sizes, leading to higher costs and a significant dip in stock value.