If you wondered about the scope and meaning in an organization of portfolio management the book Portfolio Management for New Products by Robert G. Cooper, Scott Edgett and Elko J. Kleinschmidt brings some good information about its meaning and explains several techniques used in the industry to improve this process.

Some excerpt from the book:

Portfolio management for new products is a dynamic decision process wherein the list of active products and R&D projects is constantly revised….
It is more than project selection, although that is part of it; it is certainly much more than annual budgeting or resource allocation across projects; it goes beyond simply developing a prioritized list of projects; it is more than strategizing and trying to arrive at the best set of projects to meet strategic needs, although strategy and strategic imperatives are certainly key components.

Three main goals of portfolio management:
Maximizing the value of the portfolio: a prime goal is to maximize the value of the portfolio against objectives, such as profitability or strategic importance

Balance in the portfolio: Portfolios can be balanced on numerous dimensions. The most popular are risk versus rewards, ease versus attractiveness, and according to breakdowns by project types, market, and product lines, long-term vs. short terms, high risk vs. low risk.

Link to strategy: Strategic alignment- strategic fit, project selection, and resource allocation reflecting the business’ strategy – are the issues here.