New Delhi, Feb. 4 -- IndiGo lost nearly four percentage points of domestic market share in December after mass flight cancellations and a sharp cut in daily departures, ceding ground to rival Air India Group, data released by the aviation regulator showed.

The country's largest airline saw its market share fall to 59.6% in December from 63.6% in November, according to monthly traffic data from the Directorate General of Civil Aviation (DGCA). This marked IndiGo's lowest monthly market share in the past two years.

By contrast, Tata-backed Air India Group gained over three percentage points during the month, emerging as the biggest beneficiary of IndiGo's operational disruption.

December's traffic data underscore how operational reliabil...