Recently reviewed some trading cases and found that many people’s understanding of the KDJ indicator still remains superficial. In fact, this tool, known as one of the “Three Treasures of Retail Investors,” can indeed help you seize many opportunities if used correctly.

I have been using KDJ for several years, and my deepest experience is that it is really very sensitive. The combination of the K line, D line, and J line can accurately reflect the overbought and oversold conditions of the market. Simply put, the K value is the fast line, the D value is the slow line used to smooth the K line, and the J value measures the divergence between K and D. When the K line breaks above the D line, it’s usually a buy signal; conversely, it’s a sell signal.

Regarding the calculation of KDJ, you don’t actually need to do it yourself. Most trading platforms have it preset, usually with parameters (9,3,3). You just need to set the period on the chart to see the trend. The core formula is to first calculate the raw stochastic value (RSV), then derive the K, D, and J values using a smoothed moving average method.

In practical trading, I most often use several judgment methods. First is the overbought and oversold zones, generally judged by the lines at 80 and 20. When the K and D lines rise above 80, it indicates the stock price has entered an overbought zone; dropping below 20 indicates an oversold zone. Sometimes I also look at the volatility of the J line; a J value greater than 100 indicates overbought, less than 10 indicates oversold.

But the most useful signals are the golden cross and death cross. A low-level golden cross (when both K and D lines are below 20 and K line breaks above D line) often predicts a reversal upward, so I consider buying at this point. A high-level death cross (when both K and D lines are above 80 and K line breaks below D line) is a sell signal. I remember during the Hang Seng Index’s rally in 2016, I used the low-level golden cross and bottom divergence to catch the reversal point, and later, through the high-level death cross, I exited in time to preserve profits.

Divergence phenomena are also very important. Top divergence occurs when the stock price makes higher highs but the KDJ makes lower highs, which is usually a sign of a decline. Conversely, bottom divergence occurs when the stock price makes lower lows but the KDJ makes higher lows, signaling a bottoming rebound. This divergence pattern has quite high accuracy.

There are also double bottoms and double tops. When KDJ is below 50 and W-shaped or triple bottom patterns appear, it indicates an imminent reversal upward; when above 80 and M-shaped or triple top patterns appear, it signals a reversal downward. The more bottoms, the larger the upward move; the more tops, the larger the downward move. I have verified this pattern many times.

However, I must honestly say that KDJ also has obvious shortcomings. In extremely strong or weak markets, it often becomes dull, giving premature buy or sell signals, leading to frequent stop-losses. Also, because it is based on historical data, its signals tend to lag, which may cause it to react too slowly in rapidly changing markets. Most importantly, KDJ should not be used alone; it can produce false signals, especially during sideways consolidation.

Therefore, my advice is that KDJ is just one tool in your toolbox. You need to combine it with candlestick patterns, volume, and other technical indicators to improve your success rate. I personally also look at moving averages, MACD, or RSI to make more comprehensive judgments. During trading, controlling risk is always more important than chasing perfect signals. If you’re interested in this method, practice more on a demo account and test these theories in real trading. Only then can you truly master the essence of KDJ.