The U.S. company owns 8.21 percent of the English Premier League club's Class A shares, listed on the New York Stock Exchange last year, according to a Securities and Exchange Commission filing. The asset manager has also invested in the Formula One motor racing business.
United are seven points clear at the top of the Premier League and have had a good start to the year commercially, signing up a series of sponsorship deals. A report this week by Forbes said that United's recent share price rise has made it the first professional sports team with a value of more than $3 billion.
The club is owned by the American Glazer family. The share listing last August used a dual structure of Class A and B shares, which left the Glazers firmly in control of the club.
The shares languished below the initial $14 price for much of last year but have surged in recent weeks to a peak of $17.75. They closed at $16.78 on Wednesday.
English soccer clubs will benefit over the next three years from enhanced television deals, while spending should be curbed by European rules punishing clubs that run up big losses.
Writing by Keith Weir; Editing by David Goodman