* Saxo Bank co-founder to sell 25.71 pct stake to Geely
* Deal marks Geely's first foray into financial services
* Geely can help Saxo Bank to grow in Asia -shareholder (Adds detail, quotes, background)
COPENHAGEN, May 5 (Reuters) - Saxo Bank co-founder Lars Seier Christensen has agreed to sell his 25.71 percent stake in the online trading platform provider to a subsidiary of Chinese carmaker Zhejiang Geely Holding Group, the unlisted Danish company said on Friday.
The investment marks Geely's first foray into financial services, but it is part of continuing Chinese expansion into European business after news this week that conglomerate HNA Group has become the biggest direct shareholder in Deutsche Bank .
Geely is better known as the owner of Volvo Cars, The London Taxi Company and its own auto brand in China.
Some Saxo Bank minority shareholders could exercise so-called tag-along rights that are expected to increase Geely's stake to 30 percent, making it the largest shareholder in the Danish company.
Despite its name, Saxo Bank derives most of its income from its online trading platforms for private foreign exchange traders and others rather than traditional banking.
Kim Fournais, who founded Saxo Bank with Christensen and Marc Hauschildt in 1992 and still owns a 25.71 percent stake, said the new shareholder could help the company with its growth ambitions.
"I am confident that partnering with Geely creates an even stronger foundation to capitalise on the many global opportunities and not least in the growing Chinese and Asian markets," Fournais said.
Saxo Bank has 1,600 employees in 18 countries and made operating revenue of 2.9 billion Danish crowns ($427.7 million) last year.
The companies declined to disclose financial terms of the deal, which is expected to be finalised in the fourth quarter. ($1 = 6.7808 Danish crowns) (Reporting by Teis Jensen, additional reporting by Rachel Armstrong; Editing by Terje Solsvik and David Goodman)