Lagging indicators, often known as trend-following indicators, do exactly what their name suggests: they track the price activity. These signs will almost never drive a security’s price. When stocks or markets exhibit robust trends, trend-following indicators perform well. As long as the trend continues, they are intended to draw traders in and hold them there. As a result, these indicators are useless in sideways or trading markets. Trend-following indicators are likely to produce a lot of false signals and whipsaws when employed in trading markets. MACD and moving averages (exponential, basic, weighted, and variable) are two common trend-following indicators.
The S&P 500 ($SPX) is seen in the above chart along with its 20- and 100-day simple moving averages. Seven signals were produced during the two years shown in the figure using a moving average crossover. The system would have made a huge profit throughout these two years. The significant trends that emerged from October 1997 to August 1998 and from November 1998 to August 1999 are to blame for this. Observe, however, that the whipsaws commence as soon as the index begins to move laterally within a trading range. Within a few days, the purchase, sell, and sell signals in November 1997, August 1999, and September 1999 were reversed. There would have been fewer whipsaws if these moving averages (50- and 200-day moving averages) had been longer.Had these moving averages been shorter (10 and 50-day moving average), there would have been more whipsaws, more signals, and earlier signals.
Benefits and Drawbacks of Lagging Indicators
The ability to spot and hold a move is one of the key advantages of trend-following indicators. Trend-following indicators have the potential to be very profitable and user-friendly if the market or securities in question develops a consistent advance. There are fewer signs and less trading activity the longer the trend.
When a security swings within a trading range, trend-following indicators lose their usefulness. The index seems to have been range-bound at least half the time in the S&P 500 sample. There have been extended periods of sideways movement, despite the index’s upward tendency from 1982 to 1999. The index fluctuated between a wide range of 85 and 110 between 1964 and 1980.
The tendency of trend-following indicators to produce signals late is another disadvantage. Much of the change has already taken place by the time a moving average crossover takes place. At 1130, the Nov-98 purchase signal was generated, which was roughly 19% higher than the Oct-98 low of 950. The risk/reward ratio may be distorted by late entrance and departure points.
The Challenge of Indicators
Sensitivity and consistency are trade-offs for technical indicators. An indication that is responsive to price changes, provides early alerts, and has few false signals (whipsaws) is excellent. An indicator will produce early indications if the sensitivity is increased by decreasing the number of periods, but the quantity of erroneous signals will rise. The frequency of erroneous signals will go down if we increase the number of periods to reduce sensitivity, but the signals will lag, which will distort the reward-to-risk ratio.
The longer a moving average is, the slower it will react and fewer signals will be generated. As the moving average is shortened, it becomes faster and more volatile, increasing the number of false signals. The same holds true for the various momentum indicators. A 14 period RSI will generate fewer signals than a 5 period RSI. The 5 period RSI will be much more sensitive and have more overbought and oversold readings. It is up to each investor to select a timeframe that suits his or her trading style and objectives.
Oscillator Types
An oscillator is a type of indicator whose value varies over time, either above or below a centerline or between predetermined levels. Oscillators cannot trend for an extended amount of time, but they can stay at extreme levels (overbought or oversold) for extended periods of time. On the other hand, a security or a cumulative indicator such as On-Balance-Volume (OBV) might trend if its value keeps rising or falling over an extended period of time.
Oscillator movements are more constrained, and sustained movements (trends), regardless of the duration, are constrained, as the indicator comparison chart illustrates. Moving Average Convergence Divergence (MACD) touched the zero line roughly eighteen times throughout the two-year period, fluctuating both above and below zero. Additionally, see that the indicator retreated each time the MACD crossed +80. MACD’s movements seem constrained, despite the fact that it has no top or lower bound on its range of values. In contrast, OBV started an upward trend in March 2003 and continued to rise gradually during the following year. Because OBV’s movements are unconstrained, long-term trends can emerge.
Oscillators come in a wide variety, with some falling under more than one category. In this article, we address two major types of oscillators: banded oscillators, which oscillate between overbought and oversold extremes, and centered oscillators, which oscillate above and below a center point or line. In general, banded oscillators are better at detecting overbought and oversold levels, while centered oscillators are better at assessing the direction of market movement.
Centered Oscillators
Above and below a central point or line, centered oscillators oscillate. These oscillators are useful for determining the direction or strength of the momentum behind a security’s movement. When a centered oscillator is trading above its center line, momentum is positive (bullish); when it is trading below its center line, momentum is negative (bearish). This is the most basic form of momentum.
MACD is an example of a centered oscillator that fluctuates above and below zero. MACD is the difference between the 12-day EMA and 26-day EMA of a security. The further one moving average moves away from the other, the higher the reading. Even though there is no range limit to MACD, extremely large differences between the two moving averages are unlikely to last for long.
MACD
MACD is unique in that it has lagging elements as well as leading elements. Moving averages are lagging indicators and would be classified as trend-following or lagging elements. However, by taking the differences in the moving averages, MACD incorporates aspects of momentum or leading elements. The difference between the moving averages represents the rate of change. By measuring the rate-of-change, MACD becomes a leading indicator, but still with a bit of lag. With the integration of both moving averages and rate-of-change, MACD has forged a unique spot among oscillators as both a lagging and a leading indicator.
ROC
Rate-of-change (ROC) is a centered oscillator that also fluctuates above and below zero. As its name implies, ROC measures the percentage price change over a given time period. For example, the 20-day ROC would measure the percentage price change over the last 20 days. The bigger the difference between the current price and the price 20 days ago, the higher the value of the ROC Oscillator. When the indicator is above 0, the percentage price change is positive (bullish). When the indicator is below 0, the percentage price change is negative (bearish).
ROC 20-period example chart from StockCharts.com
As with MACD, ROC is not bound by upper or lower limits. This is typical of most centered oscillators and can make it difficult to spot overbought and oversold conditions. This ROC chart indicates that readings above +20% and below -20% represent extremes and are unlikely to last for an extended period of time. However, the only way to gauge that +20% and -20% are extreme readings is from past observations. Also, +20% and -20% represent extremes for this particular security and may not be the same for other securities. Banded oscillators offer a better alternative to gauge extreme price levels.
Banded Oscillators
Banded oscillators fluctuate above and below two bands that signify extreme price levels. The lower band represents oversold readings and the upper band represents overbought readings. These set bands are based on the oscillator and change little from security to security, allowing the users to easily identify overbought and oversold conditions. The Relative Strength Index (RSI) and the Stochastic Oscillator are two examples of banded oscillators. (Note: The formulas and rationale behind RSI and the Stochastic Oscillator are more complicated than those for MACD and ROC. As such, calculations are addressed in separate articles.)
Stochastics/RSI
For RSI, the bands for overbought and oversold are usually set at 70 and 30 respectively. A reading greater than 70 would be considered overbought, while a reading below 30 would be considered oversold. For the Stochastic Oscillator, a reading above 80 is overbought, while a reading below 20 is oversold. Even though these are the recommended band settings, certain securities may not adhere to these ranges and might require more fine-tuning. Making adjustments to the bands is usually a judgment call that will reflect a trader’s preferences and the volatility of the security.
CCI
Many, but not all, banded oscillators fluctuate within set upper and lower limits. The Relative Strength Index (RSI) and Stochastic Oscillator, discussed above, are both range-bound by 0 and 100 and will never go higher than 100 or lower than zero. The Commodity Channel Index (CCI), on the other hand, is an example of a banded oscillator that is not range-bound. CCI measures the current price relative to the average price over a given period of time; the oscillator is considered unbound because there is theoretically no upper and lower limit on that relative price difference.
In practice though, the majority of CCI values fall between -100 and +100. These fairly consistent levels make CCI useful as a banded oscillator, and just like its range-bound relatives, it can be used to determine overbought and oversold levels. While -100 and +100 are the recommended band levels, chartists may make adjustments to the levels based on their personal trading style and the volatility of the underlying security.
Pros and Cons of Centered and Banded Oscillators
Centered oscillators are best used to identify the underlying strength or direction of momentum behind a move. Broadly speaking, readings above the center point indicate bullish momentum, while readings below the center point indicate bearish momentum. The biggest difference between centered oscillators and banded oscillators is the latter’s ability to identify extreme readings. While it is possible to identify extreme readings with centered oscillators, they are not ideal for this purpose. Banded oscillators are best suited to identify overbought and oversold conditions.
Oscillator Signals
Oscillators generate buy and sell signals in various ways. Some signals are geared towards early entry, while others appear after the trend has begun. In addition to buy and sell signals, oscillators can signal that something is amiss with the current trend or that the current trend is about to change. Even though oscillators can generate their own signals, it is important to use these signals in conjunction with other aspects of technical analysis. Most oscillators are momentum indicators and only reflect one characteristic of a security’s price action. Volume, price patterns, and support/resistance levels should also be taken into consideration.
Positive and Negative Divergences
Divergence is a key concept behind many signals for oscillators as well as other indicators. Divergences can serve as a warning that the trend is about to change or set up a buy or sell signal. There are two types of divergences: positive and negative. In its most basic form, a negative divergence is when an indicator declines while the underlying security advances. A positive divergence is when the indicator advances while the underlying security declines.
A negative divergence occurs when the underlying security moves to a new high, but the indicator fails to record a new high and forms a lower high. For momentum indicators, a negative divergence shows slowing upside momentum that can sometimes foreshadow a bearish reversal. Not all negative divergences result in good signals, especially during a strong uptrend. On the Staples (SPLS) chart above, the stock formed a higher high in September, but the MACD did not exceed its prior high. A negative divergence formed and the MACD soon moved below its signal line (red).
A positive divergence occurs when a security moves to a new low, but the indicator holds above its prior low to form a higher low. For momentum indicators, a positive divergence shows less downside momentum that can sometimes foreshadow a bullish reversal. Not all positive divergences result in good signals, especially in a strong downtrend. On the Sprint (S) chart above, the stock formed a lower low in early September, but RSI held above its prior low to form a positive divergence. Also, notice that RSI was oversold in mid-August and held above 30 in September. The subsequent move above 50 in RSI and the breakout in Sprint confirmed the signal. Sprint later moved back below its breakout and warranted a reassessment at that time.
Divergences, both positive and negative, can also form in non-momentum indicators like On Balance Volume, the Accumulation Distribution Line, the AD Line and Chaikin Money Flow. On the Expeditors (EXPD) chart above, the stock moved to a new high in September, but On Balance Volume (OBV) did not confirm with a higher high. A lower high is forming in OBV and the indicator moved below its 10-day SMA.
Overbought and Oversold Extremes
Banded oscillators are designed to identify overbought and oversold extremes. Since these oscillators fluctuate between extremes, they can be challenging to use in trending markets. Banded oscillators are best used in trading ranges or with securities that are not trending. In a strong trend, users may see many signals that are not really valid. If a stock is in a strong uptrend, buying on oversold conditions will work much better than selling on overbought conditions.
In a strong trend, oscillator signals against the direction of the underlying trend are less robust than those with the trend. The trend is your friend and it can be dangerous to fight it. Even though securities develop trends, they also fluctuate within those trends. If a stock is in a strong uptrend, buying when oscillators reach oversold conditions (and near support tests) will work much better than selling on overbought conditions. During a strong downtrend, selling when oscillators reach overbought conditions would work much better. If the path of least resistance is up (down), then acting on only bullish (bearish) signals would be in harmony with the trend. Attempts to trade against the trend carry added risk.
When the trend is strong, banded oscillators can remain near overbought or oversold levels for extended periods. An overbought condition does not indicate that it is time to sell, nor does an oversold condition indicate that it is time to buy. In a strong uptrend, an oscillator can reach an overbought condition and remain so as the underlying security continues to advance. A negative divergence may form, but a bearish signal against the uptrend should be considered suspect. In a strong downtrend, an oscillator can reach an oversold condition and remain so as the underlying security continues to decline. Similarly, a positive divergence may form, but a bullish signal against the downtrend should be considered suspect. This does not mean counter-trend signals won’t work, but they should be viewed in proper context and considered with other aspects of technical analysis.
The first step in using banded oscillators is to identify the upper and lower bands that mark the extremities. For RSI, anything below 30 and above 70 represents an extremity. For the Stochastic Oscillator, anything below 20 and above 80 represents an extremity. We know that when RSI is below 30 or the Stochastic Oscillator is below 20, an oversold condition exists. By that same token, when RSI is above 70 and the Stochastic Oscillator is above 80, an overbought condition exists. Identification of an overbought or oversold condition should serve as an alert to monitor other technical aspects (price pattern, trend, support, resistance, candlesticks, volume or other indicators) with extra vigilance.
The simplest method to generate signals is to note when the upper and lower bands are crossed. If a security is overbought (above 70 for RSI and 80 for the Stochastic Oscillator) and moves back down below the upper band, then a sell signal is generated. If a security is oversold (below 30 for RSI and 20 for the Stochastic Oscillator) and moves back above the lower band, then a buy signal is generated.
Simple signals can also be combined with divergences and moving average crossovers to create more robust signals. Once a stock becomes oversold, traders may look for a positive divergence to develop in the RSI and then a cross above 30. With the Stochastic Oscillator overbought, traders may look for a negative divergence and combine that with a moving average crossover and a break below 80 to generate a signal. (Note: The Stochastic Oscillator is usually plotted with a 3-day simple moving average that acts as the trigger line. A bullish moving average crossover forms when the Stochastic Oscillator crosses above the trigger line, while a bearish moving average crossover forms when it crosses below the trigger line.)
The Cisco (CSCO) chart shows that the Stochastic Oscillator can change from oversold to overbought quite quickly. Much depends on the number of time periods used to calculate the oscillator. A 10-day Slow Stochastic Oscillator will be more volatile than a 20-day. The thin green lines indicate when the Stochastic Oscillator touched or crossed the oversold line at 20, while the thin red lines indicate when the oscillator touched or crossed the overbought line. CSCO was in a strong uptrend at the time and experiencing little selling pressure. Therefore, trying to sell when the oscillator crossed back below 80 would have been against the uptrend and not the proper strategy. When a security is trending up or has a bullish bias, traders would be better off looking for oversold conditions to generate buying opportunities.
We can also see that much of the upside for the stock occurred after the Stochastic Oscillator advanced above 80 (thin red lines). The green circle in August shows a buy signal that was generated with three separate items: one, the oscillator moved above 20 from oversold conditions; two, the oscillator moved above its three-day MA; and three, the oscillator formed a positive divergence. Confirmation from these three items makes for a more robust signal. After the buy signal, the oscillator was in overbought territory a mere 4 days later. However, the stock continued its advance for 2-3 weeks before reaching its high.
The Microsoft (MSFT) chart reveals trading opportunities with the Relative Strength Index (RSI). Because a 14-period RSI rarely moved below 30 and above 70, a 10-period RSI was chosen to increase sensitivity. With the intermediate-term and long-term trends decidedly bearish, savvy traders could have sold short each time RSI reached overbought (black vertical lines). More aggressive traders could have played the long side each time RSI dipped below 30 and then moved back above this oversold level. The first two buy signals were generated with a positive divergence and a move above 30 from oversold conditions. The third buy signal came after RSI briefly dipped below 30. Keep in mind that these three signals were against the larger downtrend and trading strategies should be adjusted accordingly.
Centerline Crossovers
As the name implies, centerline crossover signals apply mainly to centered oscillators that fluctuate above and below a centerline. Traders have been also known to use centerline crosses with RSI in order to validate a divergence or signal generated from an overbought or oversold reading. However, most banded oscillators, such as RSI and Stochastics, rely on divergences and overbought/oversold levels to generate signals. The middle ground is a bit of a no man’s land for banded oscillators and is probably best left to other tools. For our purposes, the analysis of centerline crossovers will focus on centered oscillators such as Chaikin Money Flow, MACD, and Rate-of-Change (ROC).
A centerline crossover is sometimes interpreted as a buy or sell signal. A buy signal would be generated with a cross above the centerline and a sell signal with a cross below the centerline. For MACD or ROC, a cross above or below zero would act as a signal.
Movements above or below the centerline indicate that momentum has changed from either positive to negative or negative to positive. When a centered momentum oscillator advances above its centerline, momentum turns positive and could be considered bullish. When a centered momentum oscillator declines below its centerline, momentum turns negative and could be considered bearish.
On this Intel (INTC) chart with MACD and ROC, there have been a number of signals generated from the centerline crossover. There were a couple of excellent signals, but there were also plenty of false signals and whipsaws. This highlights some of the challenges associated with trading oscillator signals. Also, it stresses the importance of combining various signals in order to create more robust buy and sell signals. Some traders also criticize centerline crossover signals as being too late and missing too much of the move.
A centerline crossover can also act as a confirmation signal to validate a previous signal or reinforce the current trend. If there were a positive divergence and bullish moving average crossover, then a subsequent advance above the centerline would confirm the previous buy signal. Failure of the oscillator to move above the centerline could be seen as a non-confirmation and act as an alert that something was amiss.
On the Intel (INTC) chart with MACD, the centerline crossover acts as the third in a series of bullish signals.
- The higher low forming signaled a potential positive divergence.
- The bullish moving average crossover confirmed the positive divergence.
- The bullish centerline crossover reinforced the move.
Some traders would worry about missing too much of the move by waiting for the third and final confirmation. However, this can be a more reliable signal and help to avoid whipsaws and false signals. It is true that waiting for the third signal will reduce profits, but it can also help reduce risk. Even after the third signal, Intel still has plenty of upside left.
Chaikin Money Flow is an example of a centered oscillator that places importance on crosses above and below the centerline. Divergences and overbought/oversold levels are all secondary to the absolute level of the indicator. The direction of the oscillator’s movement is important but needs to be placed in the context of the absolute level. The longer the oscillator is above zero, the more evidence of accumulation. The longer the oscillator is below zero, the more evidence of distribution. Hence, Chaikin Money Flow is considered to be bullish when the oscillator is trading above zero and bearish when trading below zero.
On the IBM chart, Chaikin Money Flow began to turn down in July. At this time, the stock was declining with the market and the decline in the oscillator was normal. However, in the second half of August, concerns began to grow when the oscillator failed to continue up with the stock and fell below zero. As the stock advanced further, Chaikin Money Flow continued to deteriorate. This served as a signal that something was amiss.
Pros and Cons of Oscillator Signals
Banded oscillators are best used to identify overbought and oversold conditions. However, overbought is not meant to act as a sell signal, and oversold is not meant to act as a buy signal. Overbought and oversold situations serve as an alert that conditions are reaching extreme levels and close attention should be paid to the price action and other indicators.
To improve the robustness of oscillator signals, traders can look for multiple signals. The criteria for a buy or sell signal could depend on three separate yet confirming signals. A buy signal might be generated with an oversold reading, positive divergence, and bullish moving average crossover. Conversely, a sell signal might be generated from a negative divergence, bearish moving average crossover, and bearish centerline crossover.
Traditional chart pattern analysis can also be applied to oscillators. This is a bit trickier but can help to identify the strength behind an oscillator’s move. Looking for higher highs or lower lows can help confirm the previous analysis. A trend line breakout can signal that a change in the direction of the momentum is imminent.
It is dangerous to trade an oscillator signal against the major trend of the market. In bull moves, it is best to look for buying opportunities through oversold signals, positive divergences, bullish moving average crossovers and bullish centerline crossovers. In bear moves, it is best to look for selling opportunities through overbought signals, negative divergences, bearish moving average crossovers and bearish centerline crossovers.
Finally, oscillators are most effective when used in conjunction with pattern analysis, support/resistance identification, trend identification and other technical analysis tools. By being aware of the broader picture, oscillator signals can be put into context. It is important to identify the current trend or even to ascertain if the security is trending at all. Oscillator readings and signals can have different meanings in differing circumstances. By using other analysis techniques in conjunction with oscillator reading, the chances of success can be greatly enhanced.
you may be interested in this blog here:
