Book excerpt: In this long-awaited book from the world’s premier brand expert and author of the seminal work Building Strong Brands, David Aaker shows managers how to construct a brand portfolio strategy that will support a company’s business strategy and create relevance, differentiation, energy, leverage, and clarity. Building on case studies of world-class brands such as Dell, Disney, Microsoft, Sony, Dove, Intel, CitiGroup, and PowerBar, Aaker demonstrates how powerful, cohesive brand strategies have enabled managers to revitalize brands, support business growth, and create discipline in confused, bloated portfolios of master brands, subbrands, endorser brands, cobrands, and brand extensions. Renowned brand guru Aaker demonstrates that assuring that each brand in the portfolio has a clear role and actively reinforces and supports the other portfolio brands will profoundly affect the firm’s profitability. Brand Portfolio Strategy is required reading not only for brand managers but for all managers with bottom-line responsibility to their shareholders.