The Helsinki Stock Exchange, officially called Nasdaq Helsinki, is the main stock exchange of Finland. It used to be called OMX Helsinki and Nasdaq OMX Helsinki, after the merger with OMX and the Nasdaq acquisition of OMX respectively. It is one of eight stock exchanges that belong to Nasdaq Nordic, which is a subsidiary of Nasdaq that operates stock exchanges in several Nordic and Baltic countries and provides access to 80% of the Nordic and Baltic securities market. The Helsinki Stock Exchange is headquartered in Helsinki, Finland's capital and most populous city. It lists 141 companies with a market cap of EUR 232.6 billion. The exchange also houses bonds and derivatives.

Among the listings are well-known and actively traded companies such as Nokia, Fortum, Kone, the Sampo Group and Neste Oil. The exchange manages the OMX Helsinki 25 index, a market value weighted index that consists of the 25 most actively traded stocks. There is a weight limit for each company of 10%. This index was formerly known as the HEX25 and is widely seen as a benchmark for the Finnish stock market. The exchange also operates the OMX Helsinki 15, as well as an index with the 40 leading companies in terms of sustainability and several indices that reflect the performance of different sectors and industries.