Mumbai-based Tata Teleservices' stock on Thursday rose about 9 per cent amid reports that its parent Tata Group has decided to infuse Rs 4,000 crore into the company. At 2: 09 pm, the telecom firm's stock was trading at Rs 7.45 , a rise of 8.60 per cent above its previous close. The Sensex was trading at 158 points lower at 21013 points, the third day of losses after the election result-based 400 points rally on Monday.