Carlos Slim buys into 1.3 bln eur share sale by Spain's Caixabank

MADRID, Sept 23 (Reuters) - Mexican tycoon Carlos Slim bought into a 1.3-billion-euro ($1.46 billion) share sale launched by Caixabank on Thursday through his financial firm Inbursa, a source with knowledge of the operation said on Friday.

The purchase of around 100 million euros marks another of Slim's incursions into the Spanish market, where the billionaire has amassed majority stakes in builder FCC and property firm Realia and launched takeover bids for both.

The source said Slim's Grupo Financiero Inbursa was one of two institutional investors that on Thursday bought 380 million euros worth of shares in Caixabank, Spain's third largest lender.

Spanish insurance firm Mutua Madrilena said on Friday in a filing that it was one of the two investors and had invested 280 million euros.

That would leave Slim via Inbursa with the remaining 100 million euros which is equivalent to about a 0.75 percent stake in the bank.

Caixabank made the sale of its treasury stock, which was worth around 10 percent of its capital, to boost its capital reserves for its takeover bid for Portugal's Banco BPI .

Caixabank's shares were down 3.6 percent on Thursday by 1030GMT against a fall of 1.5 percent in Europe's STOXX banking index. and a 1.3 percent on Spain's blue-chip Ibex index .

Apart from Slim's new stake in Caixabank, he owns 81 percent of FCC and 67 percent of Realia both through his holding company Inversora Carso. ($1 = 0.8919 euros) (Reporting by Angus Berwick and Rodrigo de Miguel; editing by Jason Neely)