OMX Helsinki 25 is a stock market index for the 25 most traded stocks on the Nasdaq Helsinki stock exchange. It is a price return and capitalization-weighted index. The maximum weight for a single stock is limited to 10 percent. The OMXH25 index started on 4 March 1988 with a base value of 500. It is reconstituted semi-annually on the first trading day in February and August and rebalanced quarterly in February, May, August and November. The original name of the index was HEX25, but following the merger of Optionsmäklarna and Helsinki Stock Exchange, it was changed to OMXH25 on 15 November 2004. On 30 June 2014, Nasdaq launched a total return version of the OMX Helsinki 25 index, the OMX Helsinki 25 Gross Index. Unlike the regular OMXH25 index, the OMXH25GI includes reinvested dividends. Wikipedia