Ather Energy shares extended their rally on Tuesday, rising 4 percent in early trade after surging more than 14 percent in the previous session. Brokerages Nomura and HSBC raised their price targets following the electric two-wheeler maker's strong fiscal second quarter earnings. Ather Energy stock was trading at Rs 1,638 in early deals, gaining 4 percent and ranking among the top gainers on the BSE 500 and NSE 500 indices.