When a market falls sharply, someone will soon describe it as “oversold”. The word suggests a bargain and a bounce around the corner. Sometimes that is right. Often it is not. Understanding what oversold really means, and what it does not, can save beginners from one of the most expensive habits in trading: catching a falling knife.
The simple definition
A market is described as oversold when it has fallen so far, so fast, that selling looks overdone compared with its recent behaviour. The idea is that sellers have temporarily exhausted themselves, and the price may be due a rebound as it returns towards more normal levels.
Oversold is a statement about speed and stretch, not about value. A share can be oversold and still expensive. It can also be oversold and keep falling for weeks.
How traders measure it
Most traders use indicators that compare recent price moves with their usual range:
- Relative Strength Index (RSI). A popular gauge that runs from 0 to 100. Readings below 30 are commonly read as oversold.
- Distance from a moving average. When price sits unusually far below a trend line such as the 50-day or 200-day moving average, it may be stretched.
- Bollinger Bands. Price closing below the lower band suggests an unusually large move relative to recent volatility.
- Market breadth. When a very high share of stocks in an index are falling at once, the whole market can be described as oversold.
Why oversold can stay oversold
Indicators measure the past. They cannot tell you whether the reason for the fall has gone away. If a company has issued a profit warning, or an entire sector is being re-rated because investors have changed their view, the selling can continue long after an indicator flashes oversold. In strong downtrends, oversold readings can appear again and again on the way down.
This week’s sharp drop in Asian chip stocks, covered in our Morning Market Brief, is a good example of the question traders face. After a big fall, some names looked oversold. Whether that leads to a bounce depends on whether the worry about memory chip prices fades or grows.
Using oversold sensibly
Rather than treating oversold as a buy signal, experienced traders treat it as a warning not to chase the move lower and as a prompt to look for confirmation. That might mean waiting for the price to stop making new lows, for buyers to defend a known support level, or for the indicator to turn back up from oversold territory.
It also helps to consider the bigger trend. An oversold reading inside a long-term uptrend is more likely to mark a pullback worth watching. An oversold reading inside a long-term downtrend is often just a pause.
Common mistakes
The biggest mistake is buying purely because an indicator says oversold, without a stop or a plan. The second is adding more and more to a losing position as it becomes “even more oversold”, which our guide on averaging down explains in detail. The third is ignoring the news behind the fall.
The takeaway
Oversold tells you that a move has been fast. It does not tell you the move is over. Use it as one piece of evidence alongside trend, news and risk management.
If you would like to find out how disciplined your own approach is, take the free Samuel & Co Trading Trader Assessment.
