Property website Rightmove has started to build the foundations for a stock market flotation.
Mr Williams hopes to broaden Rightmove's markets
The group said it planned to list on the London market next month, in a move that reports have said could value the firm at more than £400m.
Rightmove, which was set up in February 2000, says its site has 10 million visitors a month.
The company reported revenues of £18.2m last year - almost double 2004's figure of £9.2m.
By the end of last year it had contracts with customers representing almost two-thirds of the total estimated number of estate agency offices in England and Wales, and a further 957 rental agents.
Countrywide, estate agent - 30%
Connells, part of Skipton Building Society - 30%
HBOS, bank - 30%
Royal & Sun Alliance, insurer - 10%
"We have established Rightmove as the place where buyers and sellers can view and gather information about a huge range of residential property from across the UK," managing director Ed Williams said.
"The next stage in our growth is for us to become a broadly based residential property services group."
Rightmove is currently owned by UK estate agent Countrywide, mortgage bank HBOS, Connells - part of the Skipton Building Society, and general insurer Royal & Sun Alliance. The firm did not reveal how many shares its current owners would be selling.
Mr Williams said the firm was also investing to take advantage of the potential for growth presented by the impending introduction of home information packs (HIPs).
"We intend to continue to build the website and to become a major player in the HIPs and other property data services," he added.
By June 2007 the provision of home seller packs will be a legal requirement in England & Wales.
At an expected cost of between £500 and £1,000 they are set to become a lucrative part of the market - Rightmove estimates that about 1.8 million packs will be needed each year.
"The main elements will of course be subcontracted to surveying businesses and the councils for local searches (but) we will assemble the pack and it will have a Rightmove badge on the front," Mr Williams said.