I just realized that many people still don't fully understand the KDJ indicator, even though it's very popular. In fact, it is one of the most powerful technical analysis tools I have used for short-term trading.

Looking at the structure of the KDJ indicator, these three lines behave differently. The J line fluctuates the most, followed by K, while D is the most stable. I find this quite interesting because it helps me understand why some signals are often false. When designing, the KDJ indicator focuses on the relationship between high prices, low prices, and closing prices, combining the advantages of momentum concepts and strength indicators. This allows it to analyze the market quickly and intuitively.

I mainly use the KDJ indicator for short- and medium-term trend analysis. That’s why it is widely used in stock and futures markets. Because the essence of KDJ is a concept of random volatility, it is quite accurate in capturing short-term market trends. However, on longer cycle charts, the KDJ indicator also has certain significance in predicting medium- and long-term trends.

From a technical perspective, K and D have value ranges from 0-100, but J can exceed 100 or go below 0. In terms of sensitivity, J is the strongest, followed by K, and D is the slowest. But in terms of safety, J is the weakest, K is in the middle, and D is the most stable. That’s why I have to balance speed and reliability when trading.

Now I will share some basic application points I have learned. When the weekly J line moves upward from below 0 and the candle closes positive, it’s a good buying opportunity, especially when the stock price is above the 60-week moving average. Conversely, when the weekly J rises above 100 and then drops back down with a negative candle, I need to warn about the formation of a peak.

An important thing I learned is that the KDJ indicator works best in volatile markets. When prices enter a strong upward or downward trend, the KDJ indicator becomes passive and no longer provides valid signals. That’s when I need to switch to other tools.

Regarding general rules, if D% is above 80, the market is overbought; if below 0, oversold. For J%, if above 100, it’s overbought; below 10, oversold. When K% crosses above D% upward, it’s a buy signal. When K% drops below D%, it’s a sell signal.

An interesting discovery I made is adjusting the parameters of the KDJ indicator. The default software usually uses a parameter of 9, but it has the downside of fluctuating too much and being overly sensitive, leading to many false signals. I tried parameters 5, 19, 25 and found they work much better. Different stocks and timeframes may require different parameters.

I also noticed that signals from the J value are very noteworthy. If J exceeds 100, especially for three consecutive days, the price often forms a short-term top. If J drops below 0, especially for three consecutive days, the price hits a bottom. These signals don’t appear frequently, but when they do, their reliability is very high.

I know many experienced investors are looking for J-value signals to identify the best buy and sell points. That is the true essence of the KDJ indicator. If you want to master this tool, remember that it is most suitable for short-term analysis and performs well in volatile markets. For long-term analysis, using the weekly level of the KDJ indicator is a better choice.