Benchmark indices on Tuesday opened firm, only to eke out gains as the session progressed, thanks to lack of global cues, as US stocks were shut overnight for a public holiday. BSE Sensex was trading 34.84 points, or 0.10 per cent, higher at 34,878.35. Nifty50 rose 4.05 points, or 0.04 per cent, to 10,745.60.