The price - a record US$2.45 billion, according to the Financial Times.
According to data compiled by JLL, who advised on the deal, the sale represents the largest single-tower real estate transaction in Asia Pacific to date, and the second-largest single-tower real estate transaction globally.
The deal is also the biggest in Singapore in terms of dollar amount and square footage with QIA paying US$1,960 per square foot.
John Saunders, head of Asia Pacific for BlackRock Real Estate, told the FT that he believed concerns about looming office supply in Singapore were overstated because there was little more building expansion on the horizon.
"I have a feeling we might look back at this point and say 'that marks the recovery point' for the market," he was quoted as saying. "We have dry powder in new funds that we've raised and we're actively looking at new properties in Singapore."
The 43-storey tower comprises more than 1.2 million square feet of Grade A office space and nearly 40,000 square feet of retail space.
"Asia Square is one of the most prestigious commercial developments in the region and represents a rare opportunity to acquire a premium, highly sought-after property in one of Asia's most important business and financial centres," says Stuart Crow, Head of Asia Pacific Capital Markets, JLL. "We are delighted to have worked with BlackRock and QIA on this landmark deal which, when complete, will be one of the biggest ever real estate transactions globally."
Current tenants of Asia Square Tower 1 include financial services companies Citibank and Julius Baer as well as insurance firm Marsh & McLennan.
"Singapore continues to be an attractive destination for international investors, thanks to its stable political outlook, superior infrastructure and strong economic fundamentals. Following this flagship transaction, we expect there will be increasing investor interest in Singapore prime office stock in the coming months," says Greg Hyland, head of Capital Markets, Singapore, JLL. "Looking beyond Singapore, we are seeing a growing demand from global investors looking for major single asset opportunities in the region such as Asia Square."
JLL has been the sole leasing agent and property manager of Asia Square since it opened in June 2011.