Business Groups are legally independent firms joined together by some mechanism, particularly by equity ownership, and coordinating the use of one or more resources.
My main report in this area was published in Journal of Management Studies: Collin, S-O (1998) ‘Why are there these islands of conscious power found in the ocean of ownership? Institutional and governance hypotheses explaining the existence of business groups in Sweden’, Journal of Management Studies, 35:6, pp. 719-746.
My first attempt of writing about business groups on an European level can be scrutinised here. The title of the paper is
"Corporate governance in an enlarged European Union: Business Groups creating institutional certainty and efficiency"
It has been published in Collin, S.O. (2000) ‘Corporate governance in an enlarged European Union: Business Groups creating institutional certainty and efficiency,’ in Globalisation and change: Ways to the future, Wawrzyniak, B. Leon Kozminski Academy of Entrepreneurship and Management, Warszawa, pp. 285 – 308.
My second attempt was an empirical paper in co-operation with an excellent Master student, Ivana Cesljas, about the conditions of business groups emergence in Croatia, and its actual existence. It has been published and the reference is: Collin, S-O & Cesljas, I. (2002) ‘Business group as an organisational form for corporate governance in transitional economies: The case of Croatia’, Journal of East-European Management Studies, 7:2, pp. 162 - 186.
Presently, my research about business groups is at rest. But, in a way, it is presently converted into research about business groups in municipalities, where I cooperate in a newly started research project comparing Swedish and Italian experiences. Which you can find here.