Buying on weakness and selling on strength is the hallmark of the professional trader. While the average Joe Investor attempts to buy stocks as they are climbing higher, the professional quietly waits for prices to drop in order to enter positions.
Obviously, not all declines should be bought. Sometimes a falling stock just keeps on falling until it’s close to zero. Professional traders call the attempt to buy stocks that keep dropping “trying to catch a falling knife.”
The question is how does one tell the difference between a falling knife and a simple pullback that should be bought? Here are three ways to help you tell:
 Determine what caused the pullbackIf the pullback was caused by a one-time special situation, like an earningswarning, negative rumors, or even the selling of shares by an institution, this can create an opportunity to purchase shares at a discount. However, if the negative news comes in waves or something fundamental changes at the company, this could mean that prices will continue lower. |
 Watch the 200-day simple moving averageThe basic rule of thumb with the 200-day simple moving average is that shares that are in the process of dropping and are below that moving average should not be purchased. This can act as a line in the sand between buying and selling pressure. If shares are below the 200-day moving average and start to climb higher, this can be a buy signal depending on what caused the pullback. |
 Wait for the bounceRather than trying to time the rebound, wait for it to start prior to buying. This is particularly critical with shares trading below their 200-day simple moving average. A bounce through a widely watched resistance level such as the 50-day or 200-day simple moving average can be a clear buy signal after a stock pulls back. |
A recent example of a stock that has experienced a dramatic drop but has since bounced from the lows and appears to be setting up a powerful buying opportunity is small cap Aruba Networks, Inc. (NASDAQ:ARUN).
Aruba Networks, Inc. (NASDAQ:ARUN) is a California-based provider of computer network access solutions for mobile enterprises. In other words, the company provides Wi-Fi connection products and services. It boasts a $1.8 billion market cap, $586 million in trailing 12-month revenue, and almost $441 million in total cash.
Most recently, revenue for the third quarter of Aruba Networks, Inc. (NASDAQ:ARUN)’s fiscal year 2013 grew 12%, to $147.1 million, from the same period last year. Aruba Networks, Inc. (NASDAQ:ARUN) posted a quarterly loss of $20.2 million, or 18 cents per diluted share, compared with net income of $6 million, or 5 cents a share, in the same quarter last year.
Following the May 16 release of the fiscal third-quarter results, Aruba Networks, Inc. (NASDAQ:ARUN)’s stock plunged almost 30% in one day.
In addition to the earnings miss, Aruba has been under legal pressure. A class-action lawsuit alleges the company has produced false and misleading financial information, namely that Aruba Networks, Inc. (NASDAQ:ARUN) did not disclose its primary competitor Cisco Systems, Inc. (NASDAQ:CSCO)‘s bundling advantage in the space. I’m not a lawyer, but I’m skeptical of this claim.
