Maintaing its initial gains, the Sensex at the Bombay Stock Exchange gained 196 points in afternoon deals on increased buying amid covering-up of short positions by speculators. The 30-share barometer which rose by 171 points in its previous session, firmed up by 196 to 19,451 when reports last came in.Similarly, the wide-based National Stock Exchange index Nifty moved up by 57 points to 5,912 a short while ago.