** Shares in Avanza AVANZ.ST are up 7% after gaining as much as 12%, with traders citing a report in Swedish business daily Dagens Industri on a potential buyout plan
** The newspaper says co's founder and chairman, Sven Hagstromer, plans to join forces with a venture capital company and buy Avanza out of the stock exchange
** "Hagstromer declines the report," Avanza CEO Gustaf Unger told Reuters
** Dagens Industri writes, citing several unnamed voices in the market: "In private environment, succession, European expansion and major technology investments would have been easier to implement"
** Shares in Avanza's peer Nordnet also rise 3% in morning trade
** Avanza is among top performers on Europe's benchmark STOXX 600 index .STOXX
(Writing by Agnieszka Gosciak-Rabalska, reporting by Agnieszka Olenska)
((Agnieszka.gosciak@thomsonreuters.com))