Recently, I’ve seen many traders discussing the KDJ indicator again. To be honest, this indicator does have some interesting aspects. I often use it in my technical analysis, and today I want to share my understanding and practical experience with everyone.

First, let’s talk about why KDJ is so popular. It’s known as one of the “Three Treasures of Retail Investors,” mainly because this indicator can respond quite sensitively to short-term market fluctuations, helping you identify trend reversals. The KDJ indicator is actually a stochastic indicator composed of three lines—K (fast line), D (slow line), and J (direction-sensitive line). Simply put, the K and D lines tell you whether the stock is overbought or oversold, while the J line reflects the deviation between K and D.

Regarding the KDJ formula, many people get overwhelmed just by seeing the calculation method. But the core logic is quite simple—it’s calculated by comparing the closing price’s relative position within the highest and lowest prices over a certain period. Specifically, first calculate the Raw Stochastic Value (RSV), then use a smoothed moving average to derive the K, D, and J values. In actual trading, these calculations are automated by software, and we only need to set parameters (usually 9, 3, 3) to see the corresponding trend chart.

In practice, there are several common methods for interpretation. The first is overbought and oversold signals—drawing two reference lines at 80 and 20. When K and D lines rise above 80, it indicates an overbought condition; dropping below 20 suggests oversold. This is when you should start to be cautious.

Next are the golden cross and death cross. A golden cross occurs when K and J lines are both below 20 and then break above the D line, usually indicating that the bearish momentum is weakening and the bulls are starting to fight back, making it a good buying opportunity. Conversely, a death cross happens when K and J lines, after reaching above 80, break below the D line, signaling that the bullish momentum is nearly exhausted, and it might be time to consider selling.

Another aspect I pay close attention to is divergence. A top divergence occurs when the price hits a new high but the KDJ indicator makes a new low, often signaling an impending reversal and a sell signal. Conversely, a bottom divergence happens when the price hits a new low but the KDJ makes a new high, which often indicates a bottoming out and a potential rebound, making it a good entry point.

I remember the Hong Kong Hang Seng Index in 2016 as a good example. In mid-February, the index was falling sharply, but smart investors noticed a bottom divergence pattern—while the price made lower lows, the KDJ indicator made higher lows. This divergence was a rare opportunity to build positions. Sure enough, in the following days, the index rebounded sharply, gaining over 5%. Later, a low-level golden cross appeared below 20, which was another excellent signal to add positions. By April, a death cross at high levels appeared, and savvy traders exited to lock in profits. Throughout this process, the KDJ indicator helped investors catch several key turning points.

However, I must admit that the KDJ indicator also has obvious flaws. In strongly trending or weak markets, it tends to become dull and often gives early signals, leading to frequent trades. Also, since it’s based on historical data, it can lag during rapid market changes. Most importantly, it can generate false signals, especially during sideways consolidation.

Therefore, my advice is never to rely solely on the KDJ indicator for decision-making. It’s best to combine it with other technical indicators, candlestick patterns, volume analysis, and multiple factors to reduce risk. In actual trading, I usually use KDJ to confirm trend reversals, but final buy or sell decisions should consider multiple aspects.

Ultimately, there’s no perfect indicator in the market, and KDJ is no exception. But if you understand its strengths and limitations well and apply it flexibly in practice, it can significantly improve your trading success rate. For friends who want to deepen their trading skills, I recommend practicing with a demo account multiple times to familiarize yourself with how KDJ performs under different market conditions. This will give you more confidence when trading with real money.