The company, which has holdings in various industries including autonomous underwater vehicle research, homeland security and real estate, said the new Luxembourg unit will be initially a cash shell considering a number of deals across Europe.
Thalassa said the subsidiary will provide the group with more flexibility after the UK leaves the European Union next March, allowing it to continue to trade across the bloc.
The Luxembourg listing will allow it to raise additional funds for potential deals in Europe.
“The board consider Luxembourg, lying within the EU, to be an attractive location both geographically and for the transactions under consideration,” the group said.
In morning trading, shares edged down 3.2% to 91p.