Abu Dhabi Investment Authority (Adia), one of the world's biggest sovereign wealth funds, managed more of its money in-house last year as it strengthened its capabilities and added staff in some areas, Adia said on Tuesday.

The proportion of its assets managed by external fund managers fell to 65 per cent last year from 75 percent in 2013, the authority said in its annual review.

It said this was due to "our efforts over recent years to strengthen the organisation's in-house investment and analytical expertise". Adia has 1,650 employees from 60 nationalities, the review said.

Adia did not disclose its total assets under management but the US-based Sovereign Wealth Fund Institute, which tracks the industry, estimates them at $773 billion.

The authority invests across the world, from developed and emerging market equities, fixed income and private equity to real estate and infrastructure. Fifty-five percent of its assets are invested via index-replicating strategies, it said.

The report indicated that Adia would continue to expand some of its in-house teams this year. Fixed income and treasury plans to "selectively grow the size of all teams in 2015"; alternative investments will recruit to strengthen itself in some areas, as will real estate and private equity, Adia said.

The authority's 20-year annualised rate of return rose to 7.4 per cent at the end of last year from 7.2 per cent at the end of 2013. Its 30-year annualised rate of return rose to 8.4 per cent from 8.3 per cent. – Reuters