UPDATE 1-Gas Natural sells 500 mln euro 4-year bond

(Updates with final price)

MADRID, Oct 9 (Reuters) - Spanish gas company Gas Natural

sold 500 million euros ($644.80 million) of a four-yearbond at a final price of mid-swaps plus 335 basis points and acoupon of 4.125 percent on Tuesday.

The company, rated Baa2/BBB/BBB+, started marketing thepaper with initial price guidance of 345 basis points overmid-swaps shortly before 0830 GMT, according to IFR Markets, aThomson Reuters news and market analysis service.

Barclays, CaixaBank, Citigroup, Mitsubishi and SocieteGenerale handled the sale.

The Spanish utility was last in the market in mid-Septemberwith a 7-year bond, which priced at mid-swaps plus 465 basispoints on about 4.5 billion euros of demand.

Sentiment towards corporate debt has improved since theEuropean Central Bank outlined in early September an unlimitedgovernment bond-buying programme to help weak economies.

Improved financing conditions have prompted a run of Spanishcorporate issues since the ECB announcement, including two fromTelefonica , banks Santander and BBVAand utility Iberdrola .($1 = 0.7754 euros)

(Reporting by Jesús Aguado and Paul Day; Editing by Mark Potterand Helen Massy-Beresford)