Shares in Newcastle United rallied nearly 18% on Monday amid speculation of a takeover bid for the club.
Bid rumours follow his 5-1 victory in the InterToto Cup on Saturday
The club's former chairman, businessman Sir John Hall, told the stock market that an unnamed party had showed an interest in buying up his 28.5% stake.
Shares are now at their highest level for four years, valuing them at £75.6m.
In a statement to the London Stock Exchange, Sir John said he had received an approach "which may, or may not" lead to a disposal of his stake.
At the close of trade on Monday, its share price stood nine pence higher at 59.5p.
Earlier in the day, the press reported speculation that two groups of businessmen were eying up Sir John Hall's stake.
One consortium involved a "cash-rich British entrepreneur" keen to see Kevin Keegan return to the club, according to the Daily Express.
The newspaper also claimed a Malaysian-based group is also interested in the football club and is keen to develop plans for a casino and leisure complex at St James' Park.
However, any bidder for the club would have to secure the backing of current chairman Freddy Shepherd, who holds 27% of Newcastle United's stock.
A shareholder can hold up to 29.9% of the club's stock before he or she is obliged to make an offer for the whole club.