Imagine you see a knife falling from the counter. It's dropping fast and could land anywhere! That's similar to a falling knife in the stock market. It refers to a situation where the price of a stock (or other investment) is rapidly dropping in value. This can be scary for investors, but it doesn't necessarily mean the stock is doomed.
The saying goes "don't try to catch a falling knife" because buying a stock while its price is plummeting can be risky. You might end up buying just before it hits rock bottom and lose money.
