Fundraising website JustGiving has denied rumours that it plans to float the company on the stock exchange.
The business, which has generated more than £530m for charity since it was set up in 1999, is reported to have doubled its profits in 2008.
A story in The Sunday Times at the weekend claimed "there is speculation that the company will seek to float on the stock exchange, which could provide a windfall for its founding investors".
But Anne-Marie Huby, managing director of the firm, told Third Sector: "The rumour is most definitely untrue and it is ludicrous.
"I don't know where the speculation has come from, but it is not based on anything we have said."