Фондовый индекс — indicator of the state and dynamics of the securities market. By comparing the current value of the index with its previous values, it is possible to assess the behavior of the market, his reaction to certain changes in the macroeconomic situation, various corporate events (mergers, поглощения, дробления акций, resignations and appointments of leading managers), speculative processes. Depending on whether, what securities are sampled, used in calculating the index, it can characterize the market as a whole, market for a certain class of securities (government obligations, corporate bonds, shares, etc.. P.), industry market (securities of companies of the same industry: telecommunications, transport, insurance, Internet sector, etc.. P.). Comparing the dynamics of different indices can show, which sectors of the economy are developing the fastest. The index can represent the national stock market as a whole or a specific trading floor in this market (for example, stock exchange index). Stock indices are calculated and published by various organizations, most often by news or rating agencies and stock exchanges.