Investments in power generation assets are risky due to high construction costs and long asset lifetimes. Technology diversification in generation portfolios represents one option to reduce long-term investment risks for risk-averse decision makers. In this article, we analyze the impact of market imperfections induced by risk-aversion on the long-term investment portfolio structure in the market. We show that risk-averse electricity market agents who receive a managerial profit share may shift the technology structure in the market significantly away from the welfare optimum. A numerical example provides estimates on the potential scale of this effect and discusses sensitivities of key parameters.