China Investment Corporation has acquired a 10% shareholding in the company which operates London Heathrow, through a wholly-owned subsidiary.
Heathrow Airport Holdings - which, until recently, was known as BAA - is owned by a holding company known as FGP Topco.
Spanish firm Ferrovial, which owns just under 50% of Heathrow Airport Holdings, agreed to sell 5.72% of FGP Topco to China Investment Corporation.
The Chinese company has acquired the stake through a wholly-owned subsidiary, Stable Investment Corporation.
Ferrovial gives the transaction price as £257 million ($415 million).
Stable also agreed to acquire a further 4.28% stake in FGP Topco from other shareholders in the company, for the same share value, giving the Chinese investment company an overall 10% stake in Heathrow's operator.
Ferrovial says the deal is "unconditional" and closed on 31 October.
China Investment Corporation's acquisition follows the sale of a 10.62% stake in FGP Topco to Qatar Holdings. Once this agreement is approved by European regulators, Ferrovial's indirect share of Heathrow Airport Holdings will fall to 33.65% but it will remain the operator's largest stakeholder.