By Alistair Barr

SAN FRANCISCO (Dow Jones) -- Och-Ziff Capital Management Group LLC said Monday that its main hedge fund lost 1.55% in December as assets under management dropped by a fifth.

The OZ Master Fund, Ltd. declined 1.55% last month, leaving it down 15.51% in 2008, the firm disclosed in a regulatory filing.

The OZ Europe Master Fund, Ltd. and The OZ Asia Master Fund, Ltd. lost 1.85% and 3.46% respectively in December, leaving them down 17% and 30.38% in 2008.

Assets under management declined by $5.5 billion to $22.1 billion, Och-Ziff (OZM) also reported.

Och-Ziff shares fell 5.6% to $5.08 during afternoon trading on Monday.

Click here to go to Dow Jones NewsPlus, a web front page of today's most important business and market news, analysis and commentary. You can use this link on the day this article is published and the following day.