Fag-end buying helped the Bombay Stock Exchange benchmark Sensex to rise 113 points on Thursday, to regain the 20,000-level.
The 30-share Sensex, which had dipped below the 32-month high of 20,000 in the previous session, ended with a gain of 112.78 points at 20,069.12.
The broad-based National Stock Exchange benchmark index Nifty also regained the crucial 6,000-level by adding 38.65 points to 6,029.95.
Market analysts attributed the last-minute buying to investors covering their long positions on the last day of monthly expiry in the derivatives segment.
They further said buying in the last 30 minutes reduced the impact of a weakening global trend, rising inflation and a crucial judgement on long pending disputed Ayodhya case.
The benchmark has gained by nearly 10.7 per cent in September, boosted by heavy foreign fund investment.