Many novice investors feel overwhelmed when they first open a trading platform, confronted by a chaotic array of colorful lines beneath the price chart, and their initial instinct is to close the app. However, technical indicators are not as mysterious as they appear. Prices are just numbers, and the purpose of a technical indicator is to use mathematical operations to translate these raw numbers into comprehensible concepts like trends, momentum, and overbought or oversold conditions.
Think of it like a medical check-up report. The raw data consists of figures like blood pressure and blood sugar; the indicator is the interpretation that translates those numbers into categories such as "high," "normal," or "low." Over the next few editions, we will break down the most commonly used technical indicators in investing one by one. We will avoid complex formulas and aim to explain each indicator in the most straightforward language possible. In this edition, we will thoroughly explain the two most classic indicators: KDJ and MACD. One acts as a short-term thermometer, while the other serves as a mid-term navigation system. Once you understand these two, learning other indicators will become much easier.
Understanding KDJ: The Short-Term "Thermometer"
KDJ, whose full name is the Stochastic Oscillator, was first introduced by George Lane in the 1950s. Its core logic is straightforward: if the price is rising, the closing price tends to be near the day's high; if the price is falling, the closing price tends to be near the day's low. KDJ essentially measures where the current closing price falls within a recent price range. It consists of three lines.
How is it used? Two concepts are frequently discussed regarding KDJ: overbought/oversold conditions and golden/death crosses. The KDJ values range from 0 to 100. When both the K and D values rise above 80, it suggests the short-term increase has been excessive and the asset has entered an overbought zone, increasing the probability of a pullback. Conversely, when they fall below 20, it signals an oversold zone, where the likelihood of a rebound increases. A golden cross occurs when the K line crosses above the D line from below, indicating a bullish signal, while a death cross happens when the K line crosses below the D line from above, suggesting a bearish signal.
However, a crucial detail is that the location of the cross is more important than the cross itself. A golden cross that occurs in the oversold zone is far more reliable than one that happens near the 50 level. Similarly, a death cross in the overbought zone needs to be treated with more seriousness. KDJ does have a significant weakness, however: the issue of "stalling." When a stock enters a one-way rally, such as a series of limit-up days, the KDJ can remain above 80 for an extended period. If you sell immediately upon seeing an overbought signal, you might miss out on the main upward wave. Therefore, KDJ is best suited for a ranging market; in a strong trending market, its overbought and oversold signals may become ineffective.
Exploring MACD: The Trend "Navigator"
If KDJ is a short-term indicator, then MACD is a long-time companion for medium-term investors. Its full name is Moving Average Convergence Divergence, developed by Gerald Appel in the 1970s. The underlying logic of MACD is to observe the change in the distance between short-term and long-term moving averages. When the short-term average accelerates away from the long-term average, it indicates that the trend is strengthening. When the distance between them starts to narrow, it suggests the trend is losing momentum.
The most basic use of MACD is to observe the zero line. When both the DIF and DEA lines are above the zero line, it suggests the market is in a bullish configuration; any pullback during this time is often a buying opportunity. When both are below the zero line, bearish sentiment prevails, and bounces are often opportunities to reduce positions. The rules for golden and death crosses are similar to KDJ, with DIF crossing above DEA being a golden cross and crossing below being a death cross, but again, location is important. A golden cross above the zero line is of much higher quality than one below it, as the former indicates the "end of a pullback within an uptrend," while the latter may only be a "brief rally within a downtrend."
The truly valuable use of MACD is divergence. A bearish divergence occurs when the price reaches a new high but the MACD's DIF or histogram fails to follow suit, suggesting that the momentum driving the price up is waning. Even though the price is still climbing, the "stamina" is insufficient, signaling a need for caution about a potential top. A bullish divergence is the opposite: the price hits a new low, but the MACD does not, implying that selling pressure is easing and the market may be forming a bottom.
Divergence is the essence of MACD, but it's important to recognize that divergences can occur consecutively. In a very strong trend, you might see two or three bearish divergences before the price finally stops rising. Thus, a divergence is a "warning signal" rather than an "action order." It indicates that you should be more vigilant, but it does not necessarily require you to sell all positions immediately. Another key characteristic of MACD is its lag. Because it is based on moving averages, which are inherently smoothed versions of past prices, MACD naturally lags behind the actual price action. By the time a golden cross is confirmed, the price may have already moved significantly. This determines that MACD is more suitable for trend confirmation.
Finally, a reminder: technical indicators are not a panacea. They are merely the statistical processing of historical data and cannot predict the future. Every indicator will fail at some point. It's fine to use them as a supplementary reference, but never treat them as a "holy grail" for trading. Investing involves risk; no tool can eliminate it, they can only help you see a part of the information.