The paper investigates principal-principal (PP) conflicts arising in mergers and acquisitions (M&A) in ASEAN 5 countries; Indonesia, Malaysia, Philippines, Singapore and Thailand. The issue is of importance to investors and the growth of equity markets in ASEAN countries in South East Asia and probably well beyond. Large controlling shareholders in Asian public limited corporations, according to prior research, do cause agency conflicts. However, the net effects cannot be estimated with any degree of accuracy without understanding and being able to distinguish the single effect of an investment project. The relation between large shareholders and agency conflicts is difficult to test empirically since no public information is provided at the individual investment project level, which differs from the case of corporate mergers and acquisitions (M&A) (Amihud, Lev, & Travlos, 1990). The diagnostic testing potential the analysis to utilise Hausman-Taylor (HT) technique that takes into account time variant and time-invariant data into the model analysis. PP conflicts associated with M&A were found to be rampant. These suggest consequences in terms of limited willingness to participate in shareholding as part of individuals' portfolios. Similarly, challenges regulators concerned to promote the secondary market for equities are addressed in this paper by promoting the use of dividend ratio policies as an indicator for PP conflicts.