Purpose: This study aims to examine the strategic alliance portfolio and the characters of focal firm partners in the eco-friendly car market, and also suggest the important managerial implications and suggestions for firms' managers and policy-makers using the patent information of Toyota and Hyundai as examples. This study identifies the fundamental differences in Hyundai's strategic partnerships through the comparison with Toyota's alliance portfolio. Key literature reviews: This study analyzes the configuration of alliance portfolio using the patent citation information and various patent citation indexes. Many previous studies use patent citation information to analyze the flow of technological knowledge and the relative importance of the technology that companies produce (Hall, Jaffe, & Trajtenberg, 2005). Patents contain a lot of information, which researchers use to derive multiple properties related to technological innovation or technological excellence (Ernst, 2003). Especially, the Current Impact Index (CII), the Technology Strength (TS), the Technology Independence (TI) and the Science Linkage mean the technological innovation of companies (Chang, Chen, & Huang, 2012; Z. Huang et al., 2003; Sung, Wang, Huang, & Chen, 2015). Design/ methodology/ approach: The paper employs patent data for collection of partnership data for both Hyundai and Toyota using joint patent filings, and the alliance portfolios are configured by using co-assignees as partners. In addition, we use patent citation indexes to analyze the relationship between firms' technological alliance and innovation capability. (Expected) findings/results: The results of this study show that; 1) Toyota is actively developing joint R&D activities but, Hyundai is not. Because of this, Toyota has the advantageous position to obtain knowledge and technology than Hyundai due to the high centrality in alliance portfolio. 2) The alliance portfolio of Toyota and Hyundai can be categorized four groups by the degree of collaboration and patent quality. 3) There are differences in the properties of four groups of Toyota's alliance portfolio and Hyundai's alliance portfolio. Research limitations/ implications: This study has several limitations. First, patent information indicates only the cross-section of the company's innovation. Second, joint patents are not the only outcome of joint R&D, and comprise only a very small part of the output from joint R&D activities. In spite of these limitations, the findings suggest how firms can catch up to access the automotive bioplastic market, and offers contributions to theories related to portfolios.
