Fortress Investment, the US firm, has signed a definitive agreement to acquire th portfolio management business Logan Circle Partners from Guggenheim Partners.

Fortress will pay about $21 million in cash with potential for an additional payment at the end of 2011, dependent on how the Logan business performs.

Logan Circle is a fixed income asset manager with around $12 billion in assets under management; it manages portfolios for institutional investors in strategies that include core/core plus, short, intermediate and long duration, corporate and high yield, Fortress said in a statement.

"We believe this is a unique opportunity to diversify and expand Fortress's investment management business. Logan Circle has a high quality management team and a fundamental credit focus which is complementary to our existing approach," said Daniel Mudd, Fortress's chief executive officer.

The transaction is expected to close by the end of the second quarter of 2010 and is subject to customary approvals. Fortress specializes in alternative investments, with approximately $32.0 billion in assets under management as of 30 September 2009.