UPDATE 1-Oddo's Mignon to become CEO at French bank Natixis

(Rewrites with confirmation, background, share price)

PARIS, April 29 (Reuters) - Laurent Mignon has decided to leave financial services group Oddo & Cie to become chief executive of loss-making French investment bank Natixis (CNAT.PA), the companies said on Wednesday.

Francois Perol, the head of the merged Banque Populaire/Caisse d'Epargne bank and a key aide to French President Nicolas Sarkozy, offered Mignon the post. Mignon will replace Dominique Ferrero, Natixis said in a statement.

Banque Populaire and Caisse d'Epargne together own over 70 percent of Natixis, which has required several capital injections from its parents and caused them to post historic losses earlier this year.

"This decision is in line with the formation of the new group resulting from the merger of Banque Populaire and Caisse d'Epargne and is aimed at beginning a new phase in the implementation of the Natixis restructuring plan," Natixis said.

Natixis has been hit by writedowns on assets resulting from the credit crisis. Perol was named head of the merged bank after Sarkozy deemed the situation at Natixis serious enough to intervene.

Shares in Natixis were unchanged at 1.78 euros by 0940 GMT. European banking stocks .SX7P were 2.3 percent higher overall.

Natixis has been France's worst-performing bank stock for the last two years and first listed on the Paris stock market in December 2006 with a debut price of 19.55 euros.

Mignon's appointment will be proposed at a meeting of Natixis' supervisory board on Thursday following the company's annual shareholder meeting.

Mignon, 45, has been a managing partner at Oddo since September 2007, where he has been responsible for Oddo Asset Management and Oddo Corporate Finance.

Ferrero will become an advisor to Perol, Natixis added. (Reporting by Sudip Kar-Gupta; Editing by James Regan)