It had sold the stake to Scottish businessman Kevin Doyle but did not disclose the identity of the buyer.
The paper, co-founded by publishers Jens Torpe and Lawson Muncaster, is owned by a number of investors. Three Dutch and Russian banks backed the paper's launch by providing between £5m and £10m. They own half the title, while the founders own the other half.
Muncaster is understood to have sold his five per cent stake to Doyle in 2006. Doyle paid about £400,000 for it when the business was valued at £10m. Today it is valued at £20m.