“…When firms maintain multiple alliances at the same time, a focus on the egocentric network of the firm or the so-called alliance portfolio is called for (Wassmer, 2010). In the alliance portfolio context, diversification (APD for short) and its implication for firm performance has recently attracted attention in the literature on alliances (e.g., Baum, Calabrese, & Silverman, 2000;George, Zahra, Wheatley, & Khan, 2001;Goerzen & Beamish, 2005;Jiang, Tao, & Santoro, 2010;Lee, 2007;Sarkar, Aulakh, & Madhok, 2009;Terjesen, Patel, & Covin, 2011;Wassmer & Dussauge, 2011). This line of research, central to this study, looks outside the boundaries of the firm and considers the diversification of external partners as a vehicle to access external-party resources that are not otherwise available (Das & Teng, 2000;Lavie, 2006).…”