A follower in a market always uses a bundling strategy as a marketing strategy to increase profit and to change its market status. In this paper, the relationship between the main goods and bundling goods is substitutive, independent, or complementary. A Stackelberg game is applied to capture the competitive relationship between a leader and a follower. A follower uses a bundling strategy as a marketing strategy, but a leader does not. This study reveals that a follower will become a leader when he (or she) sells two products that are low substitution goods. However, it induces a social welfare to decrease when a follower bundles goods. This paper illustrates that a bundling action can invert a follower&r...