It was a classic 'hold the front page' moment. The biggest news in domestic sport since Britain was awarded the Olympic Games in 2005.

Opponents breathed a sigh of relief as the most influential figure in European football finally announced his retirement, while his club’s supporters wondered whether this potentially pivotal moment represents the beginning of the end. They’re comforted only in the knowledge that such a fate is unlikely to befall them just yet.

As everyone knows, Sir Alex Ferguson has brought unimaginable success and silverware to Old Trafford. And, while enjoying an enviable flow of on-field victories, the Manchester United brand and business has benefited from the simultaneous tidal wave of income which flooded relentlessly into its coffers via the Premier League and then the Champions League.

The Scot’s incredible drive, commitment, spirit and ability to perform year-in, year-out, has been responsible for turning Manchester United from also-rans into the most dominant football club in England for two decades.

It was his uncanny knack of identifying outstanding talent that transformed United off the pitch too and persuaded the Glazer family to borrow enormous sums of money to acquire football’s most consistent money-making machine.

According to a study published by Brand Finance, Manchester United are the most valuable football club on earth, worth more than $850 million. Their nearest rivals in the company’s hybrid brand league table are Bayern Munich.

David Haigh, Brand Finance’s chief executive, summed United’s international ambitions up when commenting upon his firm’s study. “The two top teams [in the table] operate different marketing strategies,” he said. “Bayern prioritise [their] domestic fan base whilst United concentrate on global opportunities.”

That last line says it all. Manchester United’s shares are listed on the New York Stock Exchange (NYSE) and, as speculation mounted early on Wednesday that Sir Alex was on the cusp of retiring, the club’s response had to be unequivocal.

There are specific rules regarding how a public company must deal with market rumours or unusual market activity and the NYSE is clear on how its constituent members must react: “If rumours or unusual market activity indicate that information on impending developments has leaked out, a frank and explicit announcement is clearly required. If rumours are in fact false or inaccurate, they should be promptly denied or clarified.”

Given this strict rule, it was clear that Manchester United had to make an announcement prior to the US stock market opening at 2.30pm UK time on Wednesday.

Of course, Sir Alex had to retire at some point, a possibility made very clear in the prospectus prepared by Manchester United and in roadshows conducted by the company’s brokers prior to the float on the New York market last year. It made provision for, and explained, future risks.

It was evident from this document that while the loss of players such as Rooney could affect the club’s on-field short-term performance, it was not necessarily the departure of any member of the playing staff, but of Sir Alex Ferguson himself that would affect its share price.

The reasons are clear. Without this tough-as-teak former union man, it’s probable that Manchester United would not have achieved one quarter of what they have done under his guidance.

It’s highly unlikely that longer-term shareholders will be persuaded to sell on the back of Wednesday's announcement; they’ll be watching more carefully as United undergo a transition phase which, obviously, will involve the appointment of a new manager.

Nevertheless, the new man must address the equivalent of football’s mission impossible: follow Sir Alex Ferguson.

Manchester United’s share price has rallied of late. Since hitting a low of $12 last September, the shares have increased in value by more than 56% as the club cantered towards another league title while off the pitch, it signed new deals with a raft of commercial sponsors and partners.

The club recently announced a 32% increase in revenue for the third quarter and is on course to enjoy revenues of between £350 and £360 million for the year end.

Whomever takes the helm at Old Trafford, should he achieve only a tiny proportion of what the man from Govan has done, then investors are likely to remain content.

Bookmakers believe it’s a straight forward scrap between Everton’s David Moyes, whose odds shortened steadily Wednesday afternoon, and the Special One himself, Real Madrid’s Jose Mourinho.

The appointment of Moyes is not without risk. Everton’s manager has performed minor miracles at Goodison Park despite enjoying limited transfer funds and operating with one of the top flight’s lowest wage budgets. He too is tenacious, stubborn and obstinate, features that have made Sir Alex perhaps Britain’s greatest-ever manager.

However, shareholders are concerned that Moyes has never performed with distinction in European competition, nor has he delivered the title to Evertonians.

Yet there are marked similarities between the pair. Both are Glaswegians, loyal to their respective clubs and Moyes is of a similar age (50) to that of Sir Alex (44) when he took over at Manchester United.

Mourinho, by contrast, appears to have a golden touch and can point to league crowns collected in four different countries, a truly incredible record. He’s also tasted European success and manages broadcast media in particular with aplomb. Yet he appears set on taking the reins at Chelsea, the only club, apparently, that ‘loves’ him.

Manchester United shareholders would love Mourinho to become their team’s manager as he appears a safe bet in terms of on-field success, the factor which underpins commercial success elsewhere.

But the Portuguese comes with baggage and a degree of arrogance not wholly appreciated by sponsors. Furthermore, he tends not to hang around at one club for too long and would command a salary in the region of £12 million, around double that paid to Sir Alex.

From a commercial perspective, however, Mourinho’s appointment would certainly increase the club’s global brand recognition, but is this what paying supporters actually want?

There is a dilemma for shareholders and the Glazer family here.

Select Moyes and the probability is they will have a manager capable of maintaining United’s longer-term domestic hegemony.

Opt for Mourinho and the likelihood is he will be a short-term appointment, though a considerably more exciting one than the dour Moyes and, perhaps most importantly of all, a man who could pursue United’s Holy Grail: emulating Liverpool’s five European championship titles.

Whichever man the board go for, he will inevitably remain in Sir Alex’s considerable shadow for perhaps a decade.

Provided he keeps winning, neither supporters nor shareholders will care; should the club experience an on-field downturn, however, then we can expect commercial considerations to over-ride all others as a new manager is sought.