States have increasingly started to terminate and renegotiate their bilateral investment treaties (BITs). Dominant explanations have however overlooked the underlying bargaining dynamic of investment treaty negotiations. This paper argues that while states initially in a weaker negotiating position have the strongest incentives to change their existing BITs, their ability to do so is constrained by their bargaining power. Such states become more likely to demand renegotiation or exit dissatisfying BITs if they have experienced sufficient changes in their bargaining power in relation to the treaty partner. This paper identifies observable implications of the weaker states’ incentives and bargaining power constraints for adjusting their bilateral investment treaty commitments. Leveraging a panel dataset on 2,623 BITs ranging from 1962 to 2019, interaction effects between bargaining power and incentives stemming from rationalist and bounded rationality assumptions about states’ decision-making are analyzed in relation to the occurrence of renegotiations and terminations. The paper finds that change in bargaining power in relation to the treaty partner is an important factor underlying the weaker states’ ability to terminate or renegotiate BITs, contributing to the study of investment regime reform and exit from international institutions.