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Discussing stock and stock index movement: clarifying percentage vs. points?
Points are index based.  Simple take the total value of the stocks that compose the index, and set it equal to an arbitrary number. (Say 100 or 1000)  This becomes your base.  Each day, you recalculate the value of the index basket, and relate it to the base.  So if our index on day 0 was 100, and the value of the basket went up 1%, the new index would be 101 points. For the example given, the percentage change would be (133.32 -133.68  ) / 133.68 * 100% = -0.27%  Keep in mind that an index basket will change in composition over time.  Assets are added and removed as the composition of the market changes.  For example, the TSX index no longer includes Nortel, a stock that at one time made up a significant portion of the index.  I'm not sure if a percentage drop in an index is really a meaningful statistic because of that.   It is however, a good way of looking at an individual instrument.