As competition in the sector mounts rapidly from the likes of Hailo and Uber, the private equity owner of Addison Lee is considering putting the London minicab company up for sale.
An evaluation is to be conducted by Credit Suisse and is likely to be completed by Autumn this year. It is understood that a sale could raise as much as £800m.
US-based Carlyle Group bought a majority stake in the business for £300m just over a year ago.
The potential sale follows rising pressure and competition in London between black cabs and private-hire firms.
Last year, Addison Lee lost its contract with the Department for Work and Pensions which covered use by a number of Whitehall departments.
More recently, black cab drivers took to Trafalgar Square in their thousands to protest against the San Francisco-founded Uber.
The news by no means guarantees a sale of Addison Lee.
The business, founded by John Griffin in 1975, transports 10m passengers a year and saw net profit triple to £16m in the year to August 2013.
Carlyle could still look to invest further in the company with investment potentially leading to expansion of the business to other UK cities and internationally.