Mumbai, June 19 -- Shareholders selling equity in the National Stock Exchange of India Ltd (NSE) public offer are set to bag up to thousand-fold returns on their average investment costs once the exchange gets listed. For this analysis, Mint has used the approximate upper and lower ends of grey-market quotes as references, which price shares at Rs.1,800 on the lower end and Rs.2,040 on the upper end. At the higher end, the exchange will be valued at over Rs.5 lakh crore. To be sure, grey market prices are not mathematically calculated, and final price bands are set by merchant banks after accounting for multiple factors. New India Assurance Co. and National Insurance Co. hold the lowest entry basis among the selling group, with a weighted average cost of acquisition (WACA) of Rs.0.32 per share. WACA is a metric representing the average cost an investor paid for each share over time. At Rs.2,040 a share, the IPO would represent a 6,300-fold return on the acquisition cost for New India Assurance and 6,442 times for National Insurance. Both insurers acquired NSE shares in 1993. State Bank of India (SBI) is the largest selling shareholder by volume, offering 24.75 million shares. The bank acquired NSE shares between 1993 and 1999. Currently, its acquisition cost averages at Rs.0.80 per share. This results in a total estimated original cost basis of Rs.1.98 crore. Selling at Rs.2,040 yields Rs.5,049 crore-approximately 2,550-fold returns for the state lender. Other domestic institutions, including Stock Holding Corp. of India, United India Insurance, and Bank of Baroda have average cost bases below Rs.1 per share. Their implied return multiples range from around 3,800 times to 4,440 times at the maximum price threshold. International investors who acquired shares at later stages show lower return multiples due to higher initial cost bases. Temasek, through Aranda Investments (Mauritius) Pte Ltd, is looking to offload 11.25 million shares, which it acquired at an average cost of Rs.62.38. This will yield a 31.7-fold return at Rs.2,040 per share. Morgan Stanley's 16 million shares on offer may fetch a 30-fold return at the upper level. Canada Pension Plan Investment Board maintains the highest cost basis among the listed sellers at Rs.324.13 per share. The investment yields a 6.3-fold return at the upper end. CPPIB first invested in NSE in 2021. To be sure, all figures are indicative, and do not account for the stake the selling entities are holding on to. The average costs are affected by a 2024 4:1 bonus issue of NSE shares, which reduced the average acquisition cost for long-term investors....