Adds details from report.

May 20 (Reuters) - Japan's Nikkon Holdings 9072.T is weighing going private and is preparing to hold a first round of bidding in early June, Bloomberg News reported on Wednesday, citing people familiar with the matter.

Bain Capital, Warburg Pincus and Blackstone are among the funds expected to bid and Nikkon plans to hold a second round of bidding in August, Bloomberg said.

Nikkon has chosen financial advisers and set up a special committee made up of outside directors to assess the privatisation process, Bloomberg news reported.

Japan has seen a wave of private equity-backed company delistings as firms face increasing pressure from Japanese authorities to improve shareholder returns.

Reuters could not immediately verify the report.