OMX is a Swedish financial services company. It was started by Olof Stenhammar in the 1980s to introduce trading in derivatives instruments in Sweden by use of standardized options. It acquired the Stockholm Stock Exchange in 1998 and unsuccessfully attempted acquisition of the London Stock Exchange in 2001. In 2003 the Helsinki Stock Exchange was acquired and merged with the Stockholm Stock Exchange. On August 31, 2004, the brand name of the company was changed to OMX, previous names include OM HEX, OM and Optionsmarknaden (Option Market).
The company is also a world leader in financial instruments trading systems and there are two main divisions of the company. OMX Technology, which develops and markets systems for financial transactions used by securities exchanges and OMX Exchanges, which operates stock exchanges in the Nordic and Baltic countries.