Recently, I was chatting with a few traders and found that many people still have misunderstandings about the KDJ indicator. Instead of saying it’s a sophisticated technical indicator, it’s better to see it as a tool that helps us quickly identify buy and sell points. Known as one of the "Three Treasures of Retail Investors," the reason why the KDJ indicator is so popular is because it’s simple and easy to use, and it can indeed seize many opportunities in practical trading.

The KDJ indicator is actually a stochastic indicator, with three lines on the chart: the K value (fast line), the D value (slow line), and the J value. The K and D lines are mainly used to judge overbought and oversold conditions, while the J line reflects the deviation between the K and D lines. When these lines cross, it often signals a new trading opportunity. Theoretically, when the K line breaks above the D line, it’s a bullish signal indicating a buy; when it breaks below, it’s a bearish signal suggesting a sell.

Regarding the practical application of the KDJ indicator, I think there are several core judgment methods that are particularly effective. First is the overbought and oversold assessment, usually marked by the 80 and 20 lines. When the K and D lines exceed 80, it indicates an overbought condition; when they fall below 20, it indicates oversold. There are also golden crosses and death crosses: a low-level golden cross (when both K and D are below 20 and the K line crosses above the D line) is a buy signal, while a high-level death cross (when both are above 80 and the K line crosses below the D line) is a sell signal.

In addition, divergence patterns are very important. A bullish divergence occurs when the price keeps making new lows, but the KDJ indicator is at high levels, which usually signals that a bottom is near and is a good entry point. Conversely, a bearish divergence happens when the price hits new highs but the indicator weakens, indicating risk. Patterns like W bottoms and M tops are also significant: a W bottom below 50 suggests an upcoming rebound, while an M top above 80 indicates a potential decline.

The most impressive example I remember is the Hong Kong Hang Seng Index’s trend in 2016. In February, the Hang Seng was continuously falling, but when we looked at the KDJ indicator, even though the price kept making lower lows, the indicator was making higher lows—a clear bullish divergence. For ordinary traders, this might have been despairing, but for those who understand technical analysis, it was an invaluable entry point. On February 19, the Hang Seng Index shot up with a large bullish candle of 965 points, a 5.27% increase. By February 26, a golden cross appeared at a low point, prompting us to add more positions, and the next day, the index surged another 4.20%. At the end of April, a death cross formed at a high, prompting us to exit and lock in profits. In December, a double bottom pattern gave us another chance to bottom fish, and that’s how the bull market was kick-started.

However, the KDJ indicator isn’t万能. It reacts too sensitively to the market, often giving early signals, and in very strong or very weak markets, it can become sluggish, producing false signals frequently, which can cause losses. Also, it’s based on historical prices, so it has a certain lag; in rapidly changing markets, it may not react quickly enough. Most importantly, the KDJ indicator should not be used alone; it must be combined with other indicators and chart patterns to be reliable. In sideways or choppy markets, its performance is especially unstable, and it can easily give false signals.

My advice is, rather than obsessing over the KDJ indicator itself, learn how to use it effectively in practice. Combine the KDJ with candlestick charts, volume, and other technical indicators to reduce risks. There’s no perfect technical indicator in the capital markets; what we need to do is fully leverage the strengths of the KDJ and use experience to compensate for its shortcomings. True experts are those who can analyze complex market conditions with multiple tools and identify the highest probability trading opportunities.