UPDATE 1-BPCE to boost Natixis core ratio

* BPCE to exchange notes in deals up to 1.47 bln eur

* Natixis Core Tier 1 ratio to get 0.4 pct point boost

* Natixis stock down 1.2 pct, outperforms sector index

PARIS, July 6 (Reuters) - Banque Populaire and Groupe Caisse d'Epargne, which are combining to create France's No. 2 retail bank, plan to exchange notes in deals worth up to 1.5 billion euros to boost the core Tier 1 ratio at shared investment banking arm Natixis (CNAT.PA).

BPCE is launching offers to exchange up to 1.47 billion euros of new BPCE Tier 1 securities for seven issues of outstanding Tier 1 securities issued by Natixis, the banks said in a statement on Monday.

The offers will consist of new notes in four series, two denominated in euros and two denominated in U.S. dollars, which will be listed on the Luxembourg Stock Exchange, BPCE said.

The offer prices represent an average premium of 17 percent to the market prices of the existing securities, BPCE said. The new BPCE Tier 1 notes will have a coupon of 12.5 percent or 13 percent, depending on the series.

If all of the existing Natixis securities that are the subject of the exchange offers are tendered, the transactions would increase the Core Tier 1 ratio of Natixis by about 0.4 percentage points, BPCE said.

"This exchange offer gives us the opportunity to strengthen the regulatory capital structure of Natixis, which of course is a key part of our group's future," Francois Perol, who will be head of BPCE once the merger is completed, said in the statement.

The exchange offers are being launched on Monday and the offer period will close on July 31, BPCE said.

Shares in Natixis, France's fourth-largest listed bank, were down 1.2 percent at 1.30 euros by 0751 GMT, outperforming the Dow Jones European Banking index .SX7P, which was down 2.1 percent.

Natixis made a first-quarter net loss of 1.84 billion euros, hit by write-downs. [ID:nLD881297]

Natixis' recent losses led French President Nicolas Sarkozy to intervene earlier this year amid fears that Natixis could destabilise its parent shareholders, who are among France's biggest retail banks. (Reporting by James Regan; editing by Simon Jessop)