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efficient-market hypothesis,beats by dre logo, which suggests that past price movements should provide no guide
to future changes. It cannot be explained away by saying that high-performing stocks are more
risky,global beauty chi flat iron, or by arguing that the trading costs involved in such a strategy would eat up all the profits.
Although the momentum effect has been amply documented it has never been properly
explained. Perhaps investors are slow to react when the fortunes of companies change; one good
set of results can be dismissed as a fluke,san jose sharks jerseys, but after two or three bumper periods the share turns
into a wonder stock. Another possibility is that fund managers create the momentum effect by
"window-dressing" their portfolios with the market's recent favourites (it looks much better to
close a quarter owning the market leaders).
A second puzzle is why the effect has not been arbitraged away. The answer probably lies in
timing. Clearly the momentum effect cannot last for ever or share prices would head for infinity.