The family also expects the investment to help them double the value of the club over the next 10 years, ESPN reported, citing a source.
Manchester United did not immediately respond to a Reuters request for comment.
The Glazers began looking at options including new investment or a potential sale of the club in November, 17 years after they bought the 20-time English champions for 790 million pounds.
US private equity firm Carlyle Group Inc was in talks about a "major" investment as the auction of the Premier League soccer club entered its final stages, Sky News reported on Saturday.
A small portion of the club's shares is listed on the New York Stock Exchange. The market capitalisation was about $3.6 billion as of Friday's close.