InterGlobe Aviation shares fell as much as 19 per cent on Wednesday after one of the co-founders of India's largest airline, IndiGo, alleged violation of corporate governance rules at the parent group.
InterGlobe shares hit their lowest since March and were on course for their worst day since January 2016.
IndiGo co-founder Rakesh Gangwal on Tuesday asked the country's securities regulator to intervene in the matter, a move that suggests that a previously reported row between him and fellow co-founder Rahul Bhatia was escalating.
"I have vigorously attempted for almost a year to persuade the company to shore up its governance standards, and all my attempts have been thwarted by the IGE Group," Mr Gangwal said in Tuesday's letter to the Securities and Exchange Board of India, referring to Mr Bhatia's affiliate group.
Mr Gangwal and Mr Bhatia each own less than 40 per cent in InterGlobe, giving both co-founders a major say in its strategy and plans.