This paper discusses theoretical research challenges for brand alliances in the future. A research agenda with six strategies based on the identification of binary oppositions in brand alliance exploration is suggested. The research dichotomies identified and discussed are modifier versus modified brand; second, points-of-parity versus points-of-difference; third, nesting versus nested concepts; fourth, leader brands versus partner-brands; and finally, symmetric versus asymmetric brand alliance strategies and brand values versus core competencies. For each research area, a reconciling concept is identified and discussed in relation to empirical highlights. These research areas and aligned epistemological strategies can facilitate brand strategy development within the co-branding area in the future.

The concept of symbiotic marketing, implying collaboration between brands was introduced by Adler (1966). Tauber (1988) further underscored that brand leverage would be a relevant strategy for growth in a cost-controlled world. Aaker (1996) further developed the framework of brand leveraging strategies with line extensions, vertical extensions, category extensions and co-branding or the propensity to leverage the brand equity of a partner. In contemporary brand discourse, brand leverage strategies in general and brand alliances in particular are increasingly used in order to increase cash flow and touch points with the involved brands. Kapferer (2001, p. 44) argued that brand alliances and the emergence of co-brands and ingredient branding structures might change the levels of branding: "Often, brands that have been successfully positioned at ingredient level, may be tempted to change to a different strategic level and become the overall product brand".

Brand alliances have now become fully internalized into the overarching brand portfolio strategies by many companies. Brand alliances has been defined by Coke and Sinead (2000, p. 6) as: "The linking or integration of the attributes of two or more brands to offer a new or perceptually improved product to the consumer".

Brand Management Journal, Brand Equity, Brand Awareness, Brand Management, Brand Portfolio Strategies, Brand Leverage, Brand Equity Structures, Holistic Methodologies, Epistemological Strategies, Regression Analysis, Linguistic Analysis.