This thesis contributes to a better understanding of Bilateral Investment Treaties (BITs). The second Chapter investigates the potential downside of BITs on sovereign default risk. The legal risk of arbitral proceedings imposed by BITs might increase sovereign default risk. This risk channel is especially relevant in countries with low executive constraints. Even if a sovereign does not expropriate, there may be negative effects on sovereign bond prices. Thus, sovereign debt may become more expensive after a BIT signature. The third Chapter investigates how BITs affect foreign portfolio equity investment. BITs with strong investor protection increase bilateral portfolio equity investments in countries with high political risk. In low-risk countries, no effect is detected. Policymakers should consider their political risk when deciding on investment treaties. When the political risk is low, one cannot expect an investment-enhancing effect from BITs. The fourth Chapter encourages policymakers to comply with concluded investment treaties. The first arbitral proceeding permanently lowers the bilateral portfolio investments, even from countries not involved in the investment dispute. A conviction of the host state seriously deters foreign portfolio investors. However, initiating proceedings and decisions favoring the respondent state can also deter some portfolio investors. Concerning portfolio investments, policymakers should avoid arbitral proceedings as far as possible.