When a company decides to sell their shares to the public for the first time it is called an initial public offering. For quite some time, the literature on the subject has come to the conclusion that the companies going public often undervalue their share price prior to the initial public offering resulting in an abnormal positive return on the first trading day, also known as initial public offering underpricing. 

This thesis aims to study whether initial public offering underpricing occurred in the Swedish markets during the selected time period of 2000-2022. The thesis also seeked to find whether there was a significant difference in underpricing depending if the company was listed on OMX Stockholm or First north growth market. Further, with the help of previous research on the topic, a few independent variables were retrieved and later regressed against the initial return on the first trading day and thus seeing if these variables explains if a company will see an increase in the share price on the first trading day or not. The independent variables collected were age of the company at the time of the initial public offering, deal size, the market the company was listed on and lastly the year the company was listed on the stock exchange.

The study concluded that there was a significant underpricing in Swedish initial public offerings during the studied time period with an average first day initial return of 12.56%. However, the thesis further concluded that neither of the independent variables studied had a significant effect on the initial return on the first trading day. Neither could the thesis conclude that there was a significant difference in underpricing between the two studied markets, although, the sample from OMX Stockholm saw an average underpricing of 11.09% whilst first north saw an average underpricing of 13.79%.