Mukesh Ambani-led Reliance Industries has bought back shares worth more than Rs 500 crore (Rs 5 billion) between May 11 and May 24.

The company has bought back an average 7.8 million shares a day during this period, accounting to third of its volume traded on the stock exchange. Shares of India's second-most valued firm, however, have remained flat during this period.

As on May 24, RIL had purchased a total of 19.2 million shares, data from the BSE website showed. The company so far has spend over Rs 1,300 crore on the buyback.

Leading broking house Morgan Stanley has upgraded RIL from underweight to equal weight. The US-based firm says the stock trading at multi-year lows, make its valuations "compelling". It has also said in the report that buyback programme gaining momentum will see little downside for the stock.

The Rs 10,440 crore (Rs 104.4 billion) buyback programme, which has started on February 7, is slated to continue till January 19, 2013.