The share-sale of 2.44 million shares is likely to happen in a price band between Rs 1,003 and Rs 1,024 per share.
Shares of MCX, the only listed stock exchange, today closed at Rs 1,056.05, up Rs 1.35, or 0.13%.
The share-sale, which is priced at a discount of 3 to 5%, could fetch up to Rs 250 crore to NYX.
Citigroup will be the sole book running manager to the share-sale.
NYX, which had acquired the stake in the MCX in June 2008 at a price of Rs 559 per share, has most doubled its investment in MCX.