mumbai, April 9 -- The National Stock Exchange of India (NSE) has begun preparations for its initial public offering (IPO), meeting all 20 of its investment bankers earlier this week to start drafting the offer document and outline a tentative timeline for the listing, three people aware of the matter told Mint. "NSE met all 20 bankers together for the first time, where everyone agreed to a tentative timeline for the IPO," one of the people cited above said, adding that the process will begin with the identification of risks and the preparation of required disclosures, work on which is likely to begin this week. The exchange will contact all retail shareholders who wish to participate in the share sale by the end of April, a second person a...