What exactly is KDJ? I believe many traders do not understand it correctly. Especially on daily charts, there are too many invalid signals, so it is often overlooked as an indicator, but with some parameter adjustments, it can be quite useful.

First, the basics. KDJ is an indicator that studies the relationship between high, low, and closing prices, combining the concepts of momentum and moving averages. It consists of three lines: the J line reacts most sensitively, the K line is next, and the D line is the most stable. The value range for K and D is 0 to 100, while the J value can exceed 100 or drop below 0. This characteristic is what defines KDJ, but in practical terms, it is an important point.

It is suitable for short- to medium-term trend analysis and is widely used in futures and stock markets because it allows for an intuitive grasp of market momentum. However, for long-term charts, different criteria may be needed to interpret signals.

In actual usage, the J value is crucial. If the J value exceeds 100 and remains high for three consecutive days, it often indicates a short-term price increase. Conversely, if the J value is below 0 and stays low for three days in a row, a rebound at the bottom is expected. Experienced traders wait for these J signals. Although the frequency of signals is low, once they appear, their reliability is high. This is the core practical use of KDJ.

The basic signals are the golden cross and death cross. When the K line crosses above the D line, it’s a buy signal; when it crosses below, it’s a sell signal. If the D value is above 80, the market is overbought; if below 0, it is oversold.

However, with the default parameter of 9, the sensitivity is too high, leading to frequent false signals. This is why many people consider KDJ unusable. But in practice, changing the parameter to 5, 19, or 25 significantly improves performance. It’s important to adjust these flexibly depending on the stock and timeframe.

A key point to note is that KDJ is effective in volatile, uncertain markets but tends to weaken during sustained uptrends or downtrends. Also, after entering the overbought zone (K above 80), a “passivation” phase can occur where the indicator stalls, causing subsequent buy/sell signals to become ineffective.

On weekly charts, KDJ becomes a powerful tool for medium-term trend judgment. If the weekly J line drops below 0 and closes with a bullish candle, especially when the price is above the 60-week moving average, it often signals a buying opportunity. Conversely, if the J line exceeds 100 and closes with a bearish candle, caution is needed for a potential top.

Ultimately, KDJ is a practical indicator for short- to medium-term trend analysis, provided you understand the importance of parameter settings and market conditions.