Manchester United’s owners are £1.1bn in debt – £400m more than previously known – after borrowing against their shopping mall business.
BBC Panorama has unearthed evidence that the Glazer family’s debt levels may threaten their hold on the club.
A spokesman for the American family has said it holds more than £2bn in assets.
Mortgage documents seen by the programme show that the Glazers have borrowed £388m ($570m) against shopping malls and £66m ($95m) against their American National Football League team, the Tampa Bay Buccaneers.
A portion of the Glazer family’s £700m Manchester United debt will soon see them charged interest at a rate of 16.25%.
There have been growing fears among supporters that the Glazers’ leveraged buy-out of United has saddled the club with debt and seriously undermined its ability to compete for big-money transfer targets.
They point to the £80m sale of star striker Cristiano Ronaldo last year and note that he has not been replaced by a player of similar quality. Yet ticket prices have gone up by more than a third.
The club’s management denies any lack of commitment to buying new talent and says that cash is available for Sir Alex Ferguson to buy players.
City analyst Andy Green, 37, is the Manchester United supporter who first uncovered the extent of the Glazers’ debts.
Mr Green told the BBC: “They borrowed more money at inflated valuations right at the top of the cycle.
“These are people who tell us not to worry about Manchester United debt because they are great businessmen. In their core business in the US they got it absolutely wrong.”
The Glazer family’s main assets are the shopping centre business in America, First Allied Corporation, along with Manchester United and the Tampa Bay Buccaneers.
First Allied is a private business and its accounts are not publicly available. But Mr Green discovered that the Glazers’ shopping mall mortgages had been bundled with other loans as Commercial Mortgage Backed Securities.
Those bundles are publicly traded and therefore require the Glazers to provide detailed information on all the mortgages, which are then publicly available in the US.
Mr Green found mortgages – confirmed by the BBC – on 63 of 64 First Allied shopping centres, totalling £388m ($570m).
Four shopping centres – one each in Ohio, New Mexico, Texas and Georgia – have already gone bankrupt.
When they bought Manchester United in 2005, the Glazer family borrowed £500m and paid the remaining £272 million in cash.
Mr Green found that the Glazers had remortgaged 25 of their shopping centres in the six months before the takeover.
He believes the family borrowed against their US properties to pay for United: “At the time when they had to present a huge amount of cash over here in the UK they borrowed a huge amount of extra money in the US and publicly they didn’t buy anything else that year.”
United chief executive, David Gill, has said: “We’re very confident the business model we have in place will ensure the club can continue to compete at the top of football for many years to come.
“The owners have been true to their word since they took over the club in 2005. They’ve brought commercial expertise and commercial benefit to us in a numbers of areas, and we’ve seen our revenues grow significantly.”
The Glazers’ most troublesome debts are held by Red Football, the parent company that owns Manchester United.
They are payment in kind loans, or PIKs, worth £200m and the interest owing on them will soon rise to 16.25%.
Mr Gill told the BBC in January: “We don’t worry about the PIK repayment. That’s nothing to with the club.”