, commonly known as TOPIX, along with the Nikkei 225, is an important stock market index for the Tokyo Stock Exchange (TSE) in Japan, tracking all domestic companies of the exchange's First Section. It is calculated and published by the TSE. , there are 1,669 companies listed on the First Section of the TSE, and the market value for the index was ¥197.4 trillion.
The index transitioned from a system where a company's weighting is based on the total number of shares outstanding to a weighting based on the number of shares available for trading (called the free float). This transition took place in three phases starting in October 2005 and was completed in June 2006. Although the change is a technicality, it had a significant effect on the weighting of many companies in the index, because many companies in Japan have significant holdings of shares of their business partners as a part of intricate business alliances, and such shares are no longer included in calculating the weight of companies in the index.
TSE currently calculates and distributes TOPIX every second and further plans to launch a new High-Speed Index dissemination service provided at the millisecond level starting from February 28, 2011.
Topix is an American internet news media company. Topix LLC, the controlling company, has its headquarters in Palo Alto, California.
Topix began as a news aggregator which categorizes news stories by topic and geography. In the last few years, Topix changed its focus from aggregation and curation, to content creation. Topix removed the human sexuality topic, which was one of its most popular topics, from its forums on June 26th, 2016. Topix launched new entertainment-focused slideshow based sites Stars and Offbeat and has continued to launch additional new sites since 2015. Topix is in the top 100 largest US based website according to Quantcast.