The field of portfolio management owns its origins in a seminal paper written in 1952, in which Harry Markowitz  laid down the basis for the Modern Portfolio Theory (MPT). MPT allows determining the specific mix of investments generating the highest return for a given level of risk. Whereas MPT was initially developed for financial investments, in 1981, McFarlan  provided the basis for the modern field of PPM for IT projects. According to McFarlan, management should also employ a risk-based approach to the selection and management of IT project portfolios. He observed that risk-unbalanced portfolios could lead an organization to suffer operational disruptions or leave gaps for competitors to step in.
In 1992, Wheelwright and Clark  developed a framework for categorizing projects that they called the Aggregate Project Plan. This plan allows for an overview of the project portfolio along two dimensions, (1) the extent of changes made to the product, and (2) the degree of process change, leading to four categories of projects (in increasing order of change): derivative projects, platform projects, breakthrough projects, and R&D projects (for complete definitions see ). This framework can be used to identify gaps in the portfolio or potential resource shortages.