CCI said the competition assessment of the proposed combination is also guided by the market dynamics of stock exchanges.
Both bourses had sought approval from the Competition Commission of India (CCI) in June.
"... The Commission is of the opinion that the proposed combination is not likely to have an appreciable adverse effect on competition in India in any of the relevant market(s)," the order, dated August 30, said.
At present, there are four stock exchanges with nationwide terminals -- BSE, NSE, MCX-SX and USE.
"It is also observed that the stock exchanges in India are mostly vertically integrated except USE which has outsourced its operation and maintenance services and clearing and settlement functions to BSE and its subsidiaries," CCI said.
