The Sensex opened with a positive gap of 157 points at 20,970, and soon crossed the 21,000-mark to touch a fresh all-time high of 21,077. The index is now up 239 points at 21,051.HDFC Bank has rallied 2.5% to Rs 1,699.Bharti Airtel and Reliance Communications have surged around 2% each to Rs 955 and Rs 805, respectively.HDFC and ITC have advanced 1.7% each to Rs 3,165 and Rs 235, respectively.Hindustan Unilever and Satyam have gained 1.5% each at Rs 241 and Rs 420, respectively.