This paper examines the formal and informal aspects of leadership in business firm parties, utilizing the revised party model of Jonathan Hopkin and Caterina Paolucci (1999). It demonstrates under which conditions the originally informal position of the leader in the internal organisation of business firm parties can change into a formal and fully institutionalized one. The authors zoom in on the Czech Prime Minister Andrej Babiš and his movement ANO, which started as an informal fluid movement and now exercises a very tight control over its internal structure and enjoys a high level of institutionalization. This is, of course, in direct opposition to the original definition of the business firm party, i.e. having a short political lifespan and a very low level of institutionalization. Working with the theory of institutionalization (Harmel, Janda 1994), the authors argue that this transformation is a result of the fast growth of the movement at both local and regional level, which forced ANO to adopt a more rigid and organized top down structure. This included also a more formalized role of the leader.
