HONG KONG (Reuters) - China's sovereign wealth fund China Investment Corp (CIC) has sold its equity holding in Blackstone Group LP BX.N, the U.S. private equity firm said in a filing, ending an 11-year investment.

FILE PHOTO: The ticker and trading information for Blackstone Group is displayed at the post where it is traded on the floor of the New York Stock Exchange (NYSE) April 4, 2016. REUTERS/Brendan McDermid

The original agreement with Beijing Wonderful Investments - the legal entity set up by CIC to invest in Blackstone - was struck in May 2007, just before the private equity firm’s initial public offering a month later.

The pact allowed the sovereign wealth fund to own up to 9.99 percent of the private equity firm. In 2008, the wealth fund raised its stake in Blackstone to 12.5 percent, Reuters reported at that time.

CIC’s exit from Blackstone comes amid growing trade tensions between Beijing and Washington since U.S. President Donald Trump took office just over a year ago.

Trump is seeking to impose tariffs on up to $60 billion of Chinese imports and will target the technology and telecoms sectors, two people who had discussed the issue with the Trump administration said on Tuesday.

“As of February 22, 2018, Beijing Wonderful Investments no longer owned any non-voting common units,” Blackstone said in its annual report filed with the securities regulator earlier this month. It did not give details.

Beijing-headquartered CIC told Reuters late on Wednesday it “gradually divested” its stake in Blackstone according to “changes in the market” and as part of “a normal adjustment of its portfolio”.

The sovereign fund, whose assets had surpassed $800 billion by the end of 2016 thanks mainly to stronger returns from its overseas portfolios, said the firm achieved “positive returns” from its investment.

CIC and Blackstone continue to cooperate in real estate and hedge funds, as well as direct investments, it said.

A Blackstone spokesman said in a separate emailed statement on Wednesday that the U.S. private equity firm continues “to expand this important relationship as one of CIC’s major asset managers,” despite the stake sale.

The financial details of the stake sale were not immediately clear, and a person familiar with the matter said the sovereign fund had been gradually selling its shares over the last few years.

CIC, which was founded to help China boost returns on its foreign exchange reserves, had about a 4.5 percent stake in Blackstone at the end of last year, said the person, who declined to be named as the information is not public.