Norwest bought the stake from one of NSE's stakeholders IL&FS Securities Services, which handled their legal advice on the sale in-house.
Amarchand & Mangaldas & Suresh A Shroff & Co partner Cyril Shroff and associate Ipsita Dutta advised Norwest on the new foreign investment guidelines.
Shearman & Sterling Hong Kong M&A partner Paul Strecker and counsel Sidharth Bhasin led the Shearman & Sterling team for their US client Norwest, assisted by associate Joseph Tong and trainee Matthew Brown.
Bhasin said: "It's an interesting deal in its own way because it is an indication of what people are looking to do."
Norwest's 2.11 per cent minority equity stake is the first investment made in NSE under India's foreign institutional investor (FII) guidelines.
NSE had already reached the maximum permitted foreign direct investment (FDI) stake of a total 26 per cent two years ago but its 23 per cent FII allocation was still unused.
The permitted FII holding in Indian stock exchanges such as NSE was clarified in October 2008 by the Securities and Exchange Board of India (SEBI).
Bhasin added: "There are a number of investors who'd like to invest in assets but they didn't have an avenue of investing."
According to recent reports Canadian investment fund Urbana is now planning an even larger investment in NSE of up to 5 per cent, which will likely be structured along FII lines too.
Mumbay-based NSE is one of India's largest stock exchanges, alongside Bombay Stock Exchange.