bottom fishing
US /ˈbɑː.t̬əm ˌfɪʃ.ɪŋ/
UK /ˈbɑː.t̬əm ˌfɪʃ.ɪŋ/

1.
the practice of buying securities that have fallen sharply in price, with the expectation that they will soon rise again
:
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Many investors are engaging in bottom fishing in the current bear market.
•
His strategy involves aggressive bottom fishing during market downturns.