Qatar Holding, the investment arm of the Gulf state's sovereign wealth fund, has hired former Bank of America Merrill Lynch employee Michael Cho to take a senior role in its mergers and acquisitions (M&A) team.

Cho, who was co-head of Asia mergers and acquisitions at BofA Merrill until early last year, will be the point man for what is one of the world's most aggressive investors, an organisation tasked with building a portfolio of major assets, banking sources said.

One source, speaking on condition of anonymity, said Cho would be heading the fund's M&A division, a post that has been empty since 2011. Two other sources said only he would be taking a senior role in the M&A team.

The fund's spokesman was unreachable for comment. Reuters reached Cho at Qatar Holding on Wednesday, but he declined to make any comment on his role.

The tiny Arab state has already used its natural gas riches to take stakes in Credit Suisse, Royal Dutch Shell and Glencore and is a target for states and multinationals seeking buyers or extra capital.

Qatar Holding's parent, the Qatar Investment Authority (QIA), is estimated to have assets of $100-$200 billion with an investment outlay of about $30 billion every year mostly channelled through its investment arm.

The appointment comes at a time of broader transition in the wealthy Gulf state that saw the emir hand over power to his 33-year-old son Sheikh Tamim bin Hamad al-Thani last month.

Bankers and others in the investment community have speculated that the sovereign fund may take a more cautious stance as a result of the changes. - Reuters