Bloomberg newswires said investor meetings will be held in New York, Boston, Los Angeles, London and will wrap up on September 03 in Singapore.
NSB is going to the market amid some turmoil in international markets. International bond market sources say conditions are much tighter compared to when state-run Bank of Ceylon sold a 500 million US dollar bond.
International capital markets are just beginning to open after August holiday and pause following Federal Reserve monetary tightening.
Fitch Ratings has given the bond an expected rating of 'BB-'.
NSB will one of the first large below investment grade emerging market issuers to tap the markets since Fed jitters began.
NSB was initially hoping to raise a billion US dollars.
Raising a smaller volume or reducing the tenure will help bring down the rate, analysts said.
Indonesia paid 5.45 percent for a 10-year billion dollar bond in July up from 3.5 percent for a 1.5 billion bond sale in April.
Sri Lanka's National Development Bank and DFCC Bank will be looking to NSB to set the benchmark to go the market, they said.
The two banks are looking to raise 250 million US dollars each.