The collective "pump and dump": GameStop and others

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5. it can be very difficult to dissect the reasons for stock movements

for starters, after a big stock price increase, is the new price irrationally high, or was the old price irrationally low?

big price movements "without news" are often actually with news, at least from a market perspective, it's just that we only find out about it later, if ever. for instance, private hedge fund might have just made a change in its analysis of that particular stock, or the industry, and made a big change in its portfolio. or an advisor made a big recommendation about that stock to its private clients.

in at least some of these cases, there are also supply and demand matters. stocks with large short position are prone to panics because any increase can lead to a spiral of short-seller capitulating, buying to cover their positions, and driving the price even higher, causing more short-seller capitulation, etc.


or there could be manipulation going on. or a combination of legitimate and illegitimate effects.

hard to tell.