By Tom Arnold and Davide Barbuscia

DUBAI, July 27 (Reuters) - Abu Dhabi Commercial Bank ADCB.AD (ADCB), the emirate's second largest bank by assets, raised $320 million through the sale of a five-year Formosa bond, sources told Reuters on Thursday.

Several Gulf banks have made forays into the Formosa market in the past year or so, including ADCB. Formosa bonds are sold in Taiwan by foreign issuers and denominated in currencies other than the Taiwanese dollar.

The sale, which was settled on Wednesday, was placed with institutional investors, the sources said, with one adding that a Taiwanese bank arranged the deal, declining to name it.

The bank did not respond to a Reuters request for comment.

In March, ADCB raised $230 million through the sale of a five-year Formosa bond and earlier in the year it also raised around $750 million through a five-year Formosa bond.

National Bank of Abu Dhabi and Qatar National Bank have also been active in the Formosa market in the past year or so.

(Editing by Elaine Hardcastle) ((Tom.Arnold@thomsonreuters.com; +97144536265; Reuters Messaging: tom.arnold.thomsonreuters.com@reuters.net))