Recently, a friend asked me how to bottom fish in a volatile market. I found that many people’s understanding of the KD indicator still stays at a superficial level. In fact, KD is not just an overbought/oversold tool; when used correctly, it can really help you escape tops and catch bottoms.

Let’s start with the core logic of KD. It’s simply looking at where the current price is relative to a certain period in the past. It consists of two lines: K reacts quickly, D reacts slowly, both fluctuate between 0 and 100. This design is very clever because most people consider KD above 80 as overbought and below 20 as oversold, which over time forms a market consensus.

The most commonly used zone for me is the 20/80 range. When KD is below 20, the market has already fallen to a relatively low point, and selling pressure is basically exhausted. At this time, if you see the K line crossing above the D line (golden cross), the chance to enter is quite high. Conversely, when KD is above 80, buying momentum is running out, and once the K line crosses below the D line (death cross), the risk of decline increases.

But that’s not enough. The truly powerful signals are divergence signals. Sometimes, the price makes a new high, but the KD indicator doesn’t follow with a new high—that’s called bearish divergence, indicating momentum is already waning. Conversely, if the price hits a new low but KD doesn’t, that’s bullish divergence, often an excellent buy point. I’ve seen many people successfully bottom fish using the combination of bullish divergence and KD below 20.

In practical trading, I usually combine KD with RSI. When RSI shows overbought conditions, KD is above 90, and a death cross appears, this signal becomes very reliable. I’ve seen several times after such a setup, the market indeed undergoes months of correction.

However, I must remind you that KD can fail in strong trending markets. If the market is surging, KD might stay above 80 for a long time. If you stubbornly short based on overbought signals, you’ll keep getting stopped out. Also, during sideways consolidation, KD generates many false signals, with K and D lines crossing frequently, so trend judgment must be added.

Finally, my advice is: don’t rely on any single signal alone. When overbought zones, death crosses, bullish divergence, and other signals appear together—or when KD below 20 coincides with a golden cross and bullish divergence—that’s the real opportunity to act. KD reacts quickly and has clear zones, making it especially suitable for choppy markets, but it’s ultimately based on past data. True trend judgment still depends on your market intuition and overall perspective.