SYDNEY, Sept 28 (Reuters) - Australian buyout group Quadrant Private Equity has launched the process for listing its majority-owned online cosmetics shop, Adore Beauty, two sources said on Monday.

The initial public offering (IPO), which could be the country's biggest retail IPO in five years, is expected to raise about A$250 million ($176.30 million), a third person briefed on the plans said.

Morgan Stanley and UBS are managing the deal and conducting pre-deal "investor education" sessions, the three sources added.

The people, who asked not to be identified as they were not allowed to speak publicly, said the listing would be completed before the U.S. election and would value Adore at between A$700 to over A$800 million.

The IPO, expected to be priced on Thursday, could be the largest primary raising in the country this year and the biggest in the retail sector since fruit and vegetables grower Costa Group went public in 2015, according to Refinitiv data.

Media representatives for the investment banks did not immediately respond to Reuters requests for comment. Quadrant, which acquired a majority interest in Adore Beauty last year impressed by its social media-driven high-growth sales prospects, declined to comment.

The firm is now seeking to capitalise on the acceleration of e-commerce sales following the coronavirus pandemic, one of the sources added, with sales growing at an annual compound rate of about 52% since 2018 to over A$120 million this year.

Australian IPOs are down 47% so far this year to $242 million, Refinitiv records show, with the pandemic freezing new listings in the first half of the year.

Bullish market sentiment, however, particularly in the technology and e-commerce-related sectors, is encouraging some to pursue listings.

Australia's Macquarie Group is also preparing to list its majority-owned software provider Nuix in a deal that would value the data-analysis program seller at close to $1.5 billion, Reuters had reported earlier this month.

($1 = 1.4180 Australian dollars) (Reporting by Paulina Duran in Sydney; Editing by Vinay Dwivedi)