Betfair has been valued at £1.4billion after pricing its share flotation on the London stock market on Friday
The sale of 15.2 per cent of the company on Friday took place at £13 per share after earlier rising to £15.60 per share in early conditional trading - up 20% from the initial public offering price.
Betfair's owners had been considering a flotation for a number of months before announcing their plans in September.
Betfair was launched ten years ago by former professional gambler Andrew Black and Ed Wray, a former JP Morgan trader, who together own a quarter of the group and have the option to allot an additional 10.8 per cent of the company to meet surplus demand from the offering.
The flotation will see them look to expand around the world, with expansion plans for China, India and the United States in addition to Europe and Australia.
Black and Wray, who together own a quarter of the group, will reportedly sell around ten per cent of their holdings.
In its latest figures for the three months to the end of July, Betfair increased revenue by 22 per cent to £86.3million with sports betting revenue up nearly a quarter.
Betfair currently has over three million registered customers using their sports betting, poker and games websites.