Expected cut in withholding tax for debt investments.
Authorities are checking deals involving more than three dozen companies.
BofA Merrill also upgrades its price objectives for private banks, retaining ICICI Bank Ltd as its top pick, and HDFC Bank Ltd and Axis Bank Ltd as its 'preferred' names.
Investors including units of Morgan Stanley and Citigroup have agreed to buy 28.3 million shares of Bharti Infratel at Rs 230 apiece.