LONDON (Reuters) - London-based hedge fund Caius Capital on Monday said it was disappointed with the European Banking Authority’s rejection of its request to look into a complex debt instrument used by UniCredit (CRDI.MI) that the fund said was wrongly classified as core capital. Caius in May asked the EBA to investigate the 2.98 billion euro (£2.65 billion) convertible and subordinated bond, known as CASHES, which was issued in 2008. The EBA said on Friday that there was no clear evidence of a breach of Union law and that it had decided not to open a formal investigation.