(Corrects bond type, to exchangeable from convertible)
* Bonds to be priced at 20-25 pct premium
* Sale expected to be completed today
BRUSSELS, Jan 24 (Reuters) - Belgian holding company GBL will cash in almost half of its stake in French energy group GDF Suez via 1 billion euros ($1.33 billion) of exchangeable bonds, as it seeks to raise cash to diversify its portfolio.
The four-year bonds will be priced at a premium of 20 to 25 percent to GDF shares, which closed on Wednesday at just over 61 euros.
The sale represents 2.3 percent of the French group's share capital, GBL said on Thursday.
GBL, run by Albert Frere, Belgium's richest man, is aiming to sell the bonds at a yearly coupon of between 0.375 percent and 1 percent and will announce the results of the offer later on Thursday.
The company said that it considered its remaining stake in GDF to be an important asset and remained confident in the energy group's prospects.
"It is in this context that GBL has chosen a financial instrument providing exposure to the future, the share price appreciation and at the same continued collection of the dividends," Frere said in a statement.
The placement of the bonds is led by BNP Paribas Fortis, Deutsche Bank, Societe Generale Corporate & Investment Banking and UBS acting as joint bookrunners. Rothschild acts as financial adviser to GBL in connection with the placement.
GDF was not immediately available to comment. ($1 = 0.7530 euros) (Reporting By Ben Deighton; Editing by David Goodman)