Morgan Stanley downgrades Bharti Airtel to "equal-weight" from "overweight" and cuts its target price to Rs 280 from Rs 366 .

Morgan Stanley says traffic growth is coming at the expense of operating margins as tariff wars in the sector bring down average revenue per minute for voice calls.

Investment bank adds 3G rates have also been slashed in the past six months, while overall sequential data revenue growth is declining.

Bharti Airtel has suffered a rash of downgrades this month, sending shares to their lowest since October 2006 on August 10 after posting disappointing April-June earnings.

Bharti's shares down marginally.