A private equity consortium led by Permira has bought a chemicals company to add to Cognis, its global specialist chemicals producer, as part of a buy-and-build strategy to double its size ahead of flotation.

The acquisition is the first in a roll-up strategy, where a company is built up - in this case to double its worth to €6bn ($6.5bn) - before it is floated on the stock exchange. The strategy was developed in the US but has become increasingly popular in Europe where a business is often fragmented between countries.