Hero MotoCorp on Thursday announced it will buy an additional 2.2% stake in electric scooter maker Ather Energy for up to ₹124 crore. The company earlier purchased Ather shares worth ₹140 crore to raise its stake to 39.7%. Ather could file for an IPO this month to raise about $400 million at a valuation of $2 billion, NDTV Profit reported.