While there was no official word, sources said Ramkrishna has offered to quit with immediate effect despite requests by the NSE board to stay for some more time for transition. Her tenure was scheduled to end in March 2018.
Queries sent to the exchange remained unanswered in this regard, though sources said that an official announcement is expected soon.
Ramkrishna's departure comes months ahead of a planned initial public offer, which is being keenly awaited in the market as one of the biggest IPOs in recent times. Rival BSE is also in the process of launching its IPO.
Besides, NSE has been at the centre of a major debate over new regulatory framework for high frequency trades and co-location facilities, which some believe give undue advantage to some brokers and traders.
Ramkrishna, 52, has been with the NSE since its inception in 1992 and last month itself she was named Chairperson of the board of World Federation of Exchanges (WFE), a global body of more than 200 market infrastructure providers, including exchanges.
She took over as MD and CEO of NSE with effect from April 1, 2013 for a period of five years. She has also served as NSE's Joint Managing Director.
Ramkrishna has been among the select few women leaders at the helm of leading stock exchanges around the world.
She was part of the leadership team that helped set up the National Stock Exchange (NSE) in the early 90s and was only the third person to head the bourse in its entire history of about two decades.
She succeeded Ravi Narain as the head of NSE, who also served in various leadership roles at the exchange since its inception.
Narain had served as Deputy Managing Director of NSE in its first six years and as MD and CEO thereafter. Narain had succeeded R H Patil, who was the first chief of NSE.
Both Ramkrishna and Narain were part of the initial leadership team selected by the Government to set up NSE, which got incorporated in 1992 and became operational in 1994. She was also part of the team that drafted the legislative framework for the securities market regulator SEBI in 1987.
Ramkrishna also handled various operational and strategic aspects of NSE for many years during her roles as Deputy and Joint Managing Director.
She has often been named among the top women business leaders from the country in various rankings.
There are not many women leaders heading a large exchange across the world and the stock market trading business has long been considered a male-dominated area.
As per data from WFE, NSE is among the top bourses in the world in terms of equity trades and also market capitalisation.