Definition of falling knife in English:

falling knife

See synonyms for falling knife

noun

slang US Stock Market
  • A stock, share, commodity, etc., which is undergoing a rapid decline in price or value.

    So called because, just as it is safer to allow a falling knife to land before attempting to pick it up, it is typically advisable to wait until a stock, share, etc., is at its lowest point before buying into it.

Origin

1980s; earliest use found in The Washington Post.