What it is:
A falling knife describes a stock which has experienced a rapid decline in value in a short amount of time. Just like a falling knife, you don't want to catch these companies on their way down.
How it works (Example):
A stock's downward price behavior can qualify it as a falling knife for numerous reasons. In many cases, negative news about an issuing company can initially result in a stock's falling knife behavior subsequent to widespread market divestiture. Under these circumstances, the stock's price will often recuperate in the market in the wake of a positive follow-up announcement by the issuer.
Freddie Mac is a good example of a falling knife. In July 2008, as people realized the true extent of the housing crisis, Freddie Mac saw its stock price fall 77.8% in less than one month.
Why it Matters:
A falling knife represents a stock whose viability as an investment has diminished. Under certain circumstances a falling knife may represent an opportunity to purchase the stock at a low price with the distinct possibility of price recuperation and rapid capital appreciation. Like a falling knife, these companies are safe to pick up only after they've hit the floor.