Shares in Bharti Airtel fall 5 percent as regulatory concerns resurface ahead of a ministerial panel meeting on mobile spectrum auction later in the day.
Mobile permits for Bharti and Vodafone Group Plc's local unit in some key cities are due to be renewed in November next year after completing the 20-year licence period, and the government wants them to bid for airwaves that need to be renewed.
The companies have also opposed a government plan for refarming -- or replacing premium quality airwaves with relatively less-efficient airwaves -- unless the carriers buy back the premium airwaves at double the price of the less-efficient band.
"Refarming would hit Vodafone and Bharti the most," said an analyst tracking the sector at a foreign brokerage house.
Bharti also faces government fees of more than $1 billion in airwave surcharges and fines, although most of the payouts have been deferred pending court verdicts.
Some profit-taking from Tuesday's 4.2 percent gain is also seen contributing to Bharti's share fall, dealers say.