Markets maintained firm gains through the first half of trade on Friday, with the Sensex up 539.09 points or 0.70 per cent at 78,041.21 and the Nifty 50 higher by 182.10 points or 0.75 per cent at 24,357.80, as of 12.55 PM. The session so far has been marked by broad-based buying, improving market breadth, and continued strength in technology and healthcare stocks.