since all the information is in the current price, you don't have to worry about whether it went up or down yesterday, to decide what it's going to do today.

因为当前价格代表了所有信息，你就不需要去考虑昨天股价,是涨了还是跌了，再去判断它今天的价格会怎么变化。

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That would say, how much the stock changed is independent of its current price.

也就是说这个股价的改变量中,有多少是和当前价值无关的。

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