In Malaysia, many people exhibit sluggish retirement investor decisions despite the presence of investment platforms such as unit trusts, which provide a reliable source for asset accumulation. While prior literature advocates the influences of financial advisors; medical expense risk; and housing on retirement financial planning behaviours, there is a dearth of clarity on the roles these influences play in clarifying the investor behaviour aspect of retirement financial planning. This study is aimed at investigating the importance of these influences on individual retirement investor decisions through an inclusive review of relevant literature. Outcomes of the study mainly inform retirement planning researchers the value in further examining the extended lifecycle theory in the investment domain of retirement financial planning behaviour. The importance of financial advisors, housing, and medical expense risk further prove critical in explaining such behaviours, and accordingly deserves more attention in studies forthcoming. These influences are consequently proposed as factors to be considered in retirement investor decisions believed to stir decisions and in turn, wealth accumulation for late-life.