He assumes the role held by his late elder brother, Sheik Ahmed bin Zayed Al Nahyan, who died when a glider he was riding in plunged into a lake in Morocco in late March.
Sheik Hamed currently chairs the court of Abu Dhabi's crown prince, who is one of his many half brothers.
In that role, he acts as an intermediary between the influential crown prince and those looking to do business with him, said Christopher Davidson, a professor at the University of Durham who has written extensively about the United Arab Emirates.
He also sits on the sheikdom's executive council, which is responsible for the day-to-day affairs in the emirate, and has led government-run businesses, including the Higher Corporation for Specialized Economic Zones.
His handling of those roles and his close family ties to Abu Dhabi ruler and half brother Sheik Khalifa bin Zayed Al Nahyan, made him an obvious choice to take over ADIA's management following his brother's death, Davidson said.
"He was always going to be the most likely candidate," Davidson said. "He's someone who's very discreet, cautious and well-liked."
ADIA is widely considered to be the world's largest sovereign wealth fund, with estimates of its size ranging from less than $400 billion to $875 billion and beyond.
Its investments include a $7.5 billion cash injection into Citigroup Inc. in 2007. Stocks and other equities in the U.S. and Europe make up the largest class of its assets, comprising 35 to 45 percent of the fund's holdings.
Shortly before his death, Sheik Ahmed oversaw a shift toward more transparency at ADIA, the most influential of numerous investment vehicles Abu Dhabi uses to manage its oil profits.
A month ago, the fund broke with its long-standing privacy and released its first annual statement detailing its investment strategy. The report carried a rare letter from the now deceased managing director in which he warned that "considerable uncertainty remains" for the global economy in 2010.
Although the fund's managing director is responsible for ADIA's daily operations, ultimate oversight and investment strategy rests with Abu Dhabi ruler Sheik Khalifa, who is also president of the Emirates' seven-member federation, which includes Dubai.