Electricity is in today's society transmitted all around the world, and an essential part of everyday life. The nature of this utility is that it creates natural monopolies where the electricity grid resides. Since monopolies can take advantage of consumers, regulation exists to cap the revenue of the electricity distribution operators (DOs). This thesis aims to examine what factors affect the change in productivity for Swedish DOs during 2016-2020 supporting regulators and DOs in future strategic decision-making, ensuring a productive electricity market. By securing a cost effective and sufficient grid, society can commit to the transition towards electrification and continue to obtain economic growth supporting long-term welfare of society. The thesis used a quantitative method, calculating the total factor productivity through a DEA Malmquist index. Then, using a second-stage analysis, applying a multiple regression on potential factors contributing to a change in productivity on the Malmquist TFP index. The analysis shows that during 2020, a large increase in productivity was identified, but the overall productivity had not changed much during the period. R&D investments and Network losses influenced productivity. The results showed that private firms had an approximately 1% better performance than private cooperatives, but there were no signs that private firms performed better than public ones. The thesis concluded that regulatory periods most likely played a part in the sudden increase of productivity during 2020. Drivers of productivity change where investments in R&D, which potentially could increase the overall technical production frontier. In addition, decreasing network losses had a significant effect on productivity change. Results from the ownership variable showed signs that the privatization of the electricity DOs during 1990 had a small, but significantly positive effect.