Among blue-chips, TCS's stock gained 3.31 per cent to Rs 2,724, while Tata Power climbed 2.27 per cent to Rs 90 on the BSE in morning trade.
TCS was also the top gainer among the 30-Sensex blue-chips.
Shares of Tata Steel rose by 1.13 per cent and Tata Motors was up 0.63 per cent.
Tata Elxsi soared 12.58 per cent and Tata Sponge Iron rose 11.99 per cent.
Moody's Investors Service yesterday upgraded ratings of half a dozen Tata Group firms, including TCS and Tata Motors, on account of Tata Sons' track record in providing timely support to these firms.
Upward ratings' revision reflects agency's expectation of parental and systemic support in case of need, which has been exhibited both in the form of extraordinary financial support from Tata Sons, the ultimate parent, and ongoing support through their close association with the Tata brand, Moody's Investors Service had said.