The investors are also on the verge on saving the Irish business to secure funding and a long term future for around 2,500 staff at both operations.
The existing management team led by managing director Paul Kavanagh will now manage the £500m turnover building services contractor as an independent business operating in the UK and Ireland.
Endless, a private equity fund backed by blue chip US, European and UK institutions, boasts £1bn in funds under management.
The Imtech UK & Ireland deals will take the revenues across this portfolio to over £3bn.
Kavanagh said: “The business remains in a good position, with a significant order book and large projects to deliver for our clients. With the existing management team in place we are confident we can continue to grow the business”.
A spokesperson from Endless said: “Imtech UK & Ireland are profitable, well run businesses which through no fault of their own have experienced a short period of uncertainty following their Dutch parent’s insolvency.
“That was caused by troubles at the German subsidiary.
“We are moving quickly to provide Paul and his team with the funds they need to get this profitable business back to normality and properly capitalised again. We look forward to helping them grow their business in the coming years”
Imtech UK and Ireland were forced to find a buyer earlier this month after the Dutch holding company of M&E giant Royal Imtech NV was placed in bankruptcy following heavy losses in Poland and Germany over the last two years.