David Sullivan and his business partners, David and Ralph Gold, bought into Birmingham City in 1993 and floated it in on the Alternative Investment Market in 1997 amid a frenzy of football club flotations triggered by the promise of massive TV rights payments from a new deal with BSkyB.

The float made Karren Brady the youngest chief executive of a quoted company and the shares soared 8p from their 50p float price on the first day of trading, valuing the company at £29 million.

But they have slid steadily ever since, in line with other listed football clubs. The shares are not heavily traded, since fans see their certificates as a badge of loyalty and institutional investors have lost interest since there is little growth potential even though the club managed to return to the Premier League this season.

One analyst said: "Football clubs have a good predictable flow of revenue from gate takings and TV rights deals but once they reach the Premier League, much of the revenue goes straight to the players in wages."

The shares enjoyed a flurry last year, peaking just above their float price at 51p as they looked like winning promotion to the top league and after David Sullivan and the Golds said they would like to sell the club and Chinese businessman Carson Yeong said he was interested in buying.

In the end the deal never happened and the shares have trickled back down and were suspended yesterday at just 35.5p

Birmingham's last financial results for the year to the end of last August showed an operating loss of £14.2 million and a pre-tax loss of £6.5 million as the company invested in better players to help bring them back to the Premier League.

At the time David Gold said he was interested in selling, he said: "I think deep down the public have had enough of us. They think we should have mortgaged our houses to buy more players to compete with Chelsea and Arsenal. The honeymoon is long over and we're at the divorce stage now, unfortunately. And I also feel we've had no support from Birmingham council."