We are some way off getting a verdict on the High Court trial which is currently consuming Formula One boss Bernie Ecclestone's time. It is due to come to a close in early December but we already know how much money is at stake as Ecclestone has revealed that his legal costs have accelerated to more than £15.7m ($25m).

The case surrounds the sale of a major stake in F1 which was allegedly undervalued when it was sold by German bank BayernLB to private equity firm CVC in 2006. German media firm Constantin Medien had an agreement to receive 10% if the stake was sold for more than £690m ($1.1bn) but it didn't get anything since CVC paid £510m ($814m).

Constantin claims that Ecclestone and his Bambino family trust paid a £27.5m ($44m) bribe to Gerhard Gribkowsky, the banker responsible for the sale. It alleges that they did this to steer the sale to CVC which was Ecclestone's preferred buyer as it had agreed to retain him as the boss of F1.

In 2011 Constantin filed a lawsuit against Ecclestone, Gribkowsky, Bambino and its former lawyer Stephen Mullens. Speaking to Pitpass' business editor Christian Sylt in an interview for American motoring magazine Autoweek Ecclestone says "our costs are astronomical. Bambino, Mullens and me have three big law firms. I think the lawyers' costs come to more than $25m."

The stakes are high for Constantin as it will have to cover the costs if it loses the case. It only has £4.2m (€5m) of cash in the bank and in the year to 31 December 2012 it made a £4.2m (€5m) net loss on revenue of £436.5m (€520.5m). Last week the company warned that its sales in 2013 will be lower than expected and it will make another earnings loss due to poor performance in the third quarter.

According to testimony given by Constantin's supervisory board member Dieter Hahn, the litigation is being funded by the company and its single-biggest shareholder KF15, in which he has a 42.5% stake. When asked what share of the proceeds he would be entitled to from the litigation Hahn responded "I cannot tell you this. From the share of KF15 it would be 42.5%."

The remainder of the shares in KF15 are owned by the family of the late Leo Kirch a German media mogul whose company owned a majority stake in F1.

Ecclestone admits paying Gribkowsky but denies that it was a bribe. He says that Gribkowsky threatened to tell the UK tax authorities that he controlled Bambino if the money was not paid. Bambino is based offshore but Ecclestone is a UK resident so he would be liable to pay tax on the estimated £2.5bn ($4bn) in the trust if he was found to be in control of it which he strongly denies. He says he paid Gribkowsky because his false allegations would have triggered a lengthy and costly investigation.

In May Ecclestone was charged in Germany with paying the alleged bribe. However, he has not been convicted of this and authorities have not yet decided whether to bring him to trial so they will be closely watching the proceedings in London.