Spanish contractor Actividades de Construccion y Servicios (ACS) holds a 50.2% stake in Hochtief, bringing to an end a near year-long hostile takeover battle.
A Hochtief spokesman confirmed that ACS now owned the majority of its voting rights.
The German contractor has consistently fought against the unusual takeover approach, which saw ACS navigate Germany's convoluted change of control regulations - any shareholder that manages to build a 30% stake in a company is allowed to carry on buying up shares on the open market until reaching a majority, without having to make an additional tender offer.
The Hochtief spokesman said the company would not release a statement on the change of control, adding that it came as "no surprise".
ACS, which spent € 736 million during the first quarter purchasing Hochtief shares, has stated in the past that it does not intend to break up Hochtief after gaining control of the company. It said it aimed to secure the majority stake and then leave a substantial free float of shares on the market.
The protracted takeover battle has sparked an exodus of senior Hochtief figures and ACS dominated in the election of the German contractor's new supervisory board in May.
Hochtief's former supervisory board chairman Detlev Bremkamp, together with board members Hans-Peter Keitel, Heinrich von Pierer, and Wilhelm Simson stepped down as candidates, while ACS increased the number of its representatives on the eight-strong supervisory board from two to four.
In addition to these departures, three members of Hochtief's five-strong Executive Board also stepped down in April, while Hochtief CEO and executive board chairman Dr Herbert Lütkestratkötter retired from the company, despite being aged 61 - six years short of the normal German retirement age - and having occupied the post for just two years.