Brokerage firm Jefferies has suggested a 'buy' for Infosys and HCL Tech and has downgraded TCS and Tech Mahindra. Meanwhile, it maintained its 'underperform' rating on Wipro. According to Jefferies, post-Covid cost normalisation may drive margins lower and drag IT company earnings. "We cut our earnings forecasts by up to 10% on lower margin assumptions," it added.