The Helsinki Stock Exchange (HSE) has a small number of listed stocks and a low trading volume. Therefore, market inefficiencies may exist. This research uses two freestanding models to examine the speed of adjustment of share prices to the announcement of unexpected interim earnings. For both models, the adjustment of share prices to unexpected reported interim earnings is found to be delayed by a statistically significant period, beginning with the announcement date. These results suggest semistrong form inefficiencies in the HSE during a period of stable regulation.