Recently, while studying technical indicators, I recalled the tool BIAS. Honestly, many people have misunderstandings about it. The divergence rate actually tells you how far the price has moved away, but many treat it as a buy or sell signal, which often leads to heavy losses.

Simply put, the divergence rate is an indicator that measures the distance between the current price and the moving average. The formula is straightforward: (Closing Price − N-day Moving Average) ÷ N-day Moving Average × 100%. A positive value indicates the price is above the moving average (premium), while a negative value means it's below (discount). If BIAS divergence rate is 3, it means the price is 3% above the moving average.

The pitfall I encountered before was opening positions when seeing extreme divergence rates, only to be slapped by the trend. Later, I realized that the true purpose of divergence rate isn't to predict reversals but to remind you, "Hey, the price has moved too far from the moving average, be cautious."

How to judge what "too far" means? There's no absolute answer; it depends on the market type. The S&P 500 usually has extreme values around 3-5%, Bitcoin, due to high volatility, considers 8-10% as extreme, and gold ranges from 2-5%. So, the first step is to backtest your target asset to find a reasonable extreme value range.

In practical trading, I often use divergence signals. Top divergence occurs when the price hits a new high but BIAS divergence rate doesn't keep up, indicating weakening momentum and a possible pullback; bottom divergence is the opposite—price hits a new low but divergence rate doesn't, often signaling a bottom rebound. This double confirmation method is much more reliable than just looking at extreme values.

Regarding parameter settings, I recommend short-term traders use 5-day or 10-day moving averages, swing traders use 20-day, and long-term investors use 60-day. Different cycle combinations with different BIAS divergence parameters can significantly affect results.

The most practical approach is to combine extreme values with candlestick reversals. For example, during a sharp decline, if the divergence rate is already severely oversold, and then a hammer or signs of stabilization appear, you can consider entering gradually. But never look for bearish divergence at the bottom or bullish divergence at the top, as that can be easily reversed by trend forces.

Honestly, divergence rate is just an auxiliary tool; the real market driver is the trend. In a strong upward trend, prices can stay high for a long time, and divergence rates will plateau. At this point, you need to combine other signals like RSI entering oversold zones for double confirmation. Sometimes, the market consolidates sideways instead of dropping, then starts a new rally, so don’t expect prices to immediately revert to the mean.

Ultimately, BIAS divergence rate is a reminder of a market truth: prices may fluctuate wildly in the short term due to emotions, but in the long run, they will return to the mean. When used properly, it can help you enter and exit at advantageous positions, but always remember—it’s just a reference, not a holy grail.