Abstract
When corporations develop multiple businesses, they become conglomerates. Companies such as Apple, Google, and Amazon have become emerging conglomerates by expanding their business toward several new fields. Although conglomerates suffer from discounts in the stock market, their productivity and efficiency depend on effectively managing sub-businesses. Conglomerates must synergize through cross-business collaborations, where middle managers play a significant role in strategy realization. However, little research has been conducted on middle managers’ strategic role in the success of conglomerates. This multi-case qualitative study is designed to address this gap. This study reveals that middle managers are important for conglomerates in creating synergies. By developing 11 themes, this study thematically categorizes related development programmes and corporate initiatives for middle managers to create cross-business synergies. Finally, it demonstrates a three-step process for human resource development managers and corporate executives to evaluate whether their human resource development strategies are adequately established. In addition, the results reveal two categories of managerial strategy for middle manager development — collaborative and open/flexible management strategies.