Dragados accepted BAM's offer for HBG this week, in a deal that would reduce the Dutch firm's debt and allow it to increase profitability.
BAM, whose operations are confined to the Benelux countries, is half the size of HBG. It has a turnover of £1.8bn compared with HBG's £3.6bn. The deal, which will go to BAM shareholders for approval next month, would result in HBG's former UK chief executive, Adrian Franklin, joining BAM's main board. BAM said the deal would not lead to any redundancies.
HBG's UK chief executive, Brian May, was philosophical about the latest twist at his parent firm. He said: "The uncertainty over our future doesn't help but I can honestly say it has had little influence on our business.
"We are pretty self-sufficient in the UK – there is a degree of detachment from our shareholders."
The BAM bid is the latest development in a topsy-turvy period for HBG, which began when another Dutch rival Heijmans launched an unsuccessful bid for it last June.