Manchester United would fetch a record amount for a football club should their American owners sell the English giants after 17 years at the helm, analysts said Wednesday.

The Premier League outfit announced late Tuesday they were considering "all strategic alternatives, including new investment into the club, a sale, or other transactions involving the company".

Analysts said the Glazer family could make around £5 billion ($6 billion) from the sale of a club it spent £790 million to buy, largely with debt, in 2005.

British billionaire and United fan Jim Ratcliffe is seen as a front runner for the club, which has fallen behind English rivals Liverpool and Manchester City in trophies won and stadium modernisation.

Ratcliffe, who owns the Ineos chemical group, expressed interest in buying United after his unsuccessful bid for another Premier League team, Chelsea, in May. The London club eventually went for a world-record £2.5 billion.

Simon Chadwick, professor of sport and geopolitical economy at SKEMA Business School, said interest would likely also come from outside the United Kingdom.

"I can imagine that billionaires in South East Asia, from Malaysia or Indonesia where United have a lot of supporters, would be interested. That or a consortium of US investors," he told AFP.

Chadwick added that the Glazers may believe the club has reached its peak value after Europe's elite teams failed to win support for a Super League, and with United needing big investment.

"The Super League discussion will continue to rumble on, until it either happens or doesn't, but these are harsh economic times and football is a high-cost industry," he said.

United's "Old Trafford (stadium) needs massive investment. We have seen Real Madrid and Barcelona take action to modernise their stadiums and in England, look at Tottenham. who are now in a position to also make revenue from NFL matches".

The Red Devils are also seeking a new star after announcing on Tuesday the immediate departure of Cristiano Ronaldo after his fallout with manager Erik ten Hag.

- 'Inflated valuations' -

New York-listed United is valued at around $2.5 billion but should be able to command far more in a sale thanks to the recent purchase of Chelsea.

"You would imagine any sale would involve a significant premium," Craig Erlam, analyst at Oanda trading group, told AFP.

"The Chelsea sale appears to have inflated valuations, bizarrely, given it was a fire sale."

The club was sold after the UK government sanctioned previous owner Roman Abramovich, a Russian, following Moscow's invasion of Ukraine.

An American consortium led by Todd Boehly bought the team and pledged to invest a further £1.75 billion on players and infrastructure.

Liverpool could also soon be on the market after American owners Fenway Sports Group confirmed it was looking for a big return on its £300-million outlay 12 years ago.

The Premier League is the richest in the world thanks to multi-billion-dollar television deals in the UK and abroad.

A year ago, a Saudi-led consortium bought Newcastle United and has begun investing in the team.

Manchester City has meanwhile topped Deloitte's international Football Money League for the first time after emerging from the coronavirus crisis in a stronger position than its rivals.

The Premier League champions, bankrolled by Abu Dhabi owners, are only the fourth club to top the rankings after Real Madrid, Barcelona and Manchester United.

- Shares rally -

For the 2021/22 season, Manchester United's revenue came in at £583 million. However, its net debt increased to around £515 million.

"The owners of Manchester United are hoping the urge to shop will extend to those with very deep pockets," said Susannah Streeter, senior investment and markets analyst at Hargreaves Lansdown.

Shares in Manchester United jumped 14 percent Tuesday ahead of the Wall Street close and by a further 11 percent in after-hours trading.