American football outfit Dallas Cowboys was second on the Forbes list, valued at 2.1 billion dollars, Sport24 reports.
A recent rush in the stock price of the 19-times English champions has boosted the team's value to 3.3 billion dollars, according to a story posted on the magazine's website.
United's most recent quarterly report four months ago listed their long-term outstanding debt at 560 million dollars.
Shares of the team were offered to the public last August at 14 dollars but are just under 17 dollars, boosting the wealth of the owners Glazer family, which has voting control of almost all of the team, the paper said.
Earnings dropped in the first quarter due to reduced television revenue, but Forbes credited the stock boost in part to bright prospects from new sponsor deals with China Construction Bank and Japan's Kansai, the paper concluded. (ANI )