乖离率（英语：Bias Ratio, BIAS），代表当日股票收盘价和移动平均线的差距，以分析股价偏离的程度。

当股价和移动平均线的差距愈远时，乖离率愈大，代表股价即将有修正偏离的可能。当乖离率呈现过高或过低情况时，股价均会产生反转的修正走势。

「正乖离」越大表示「超买」（Overbought），将有下跌的压力；「负乖离」越小表示「超卖」（Oversold），将有上升的动能，此时股价将会有向平均成本移动作调整的机会。

单独使用乖离率会有买卖点不明确的缺点，仅能解释成发生反转的机会增加，尚需佐以经验法则和其他分析工具来作判断。

The bias ratio is an indicator used in finance to analyze the returns of investment portfolios, and in performing due diligence.

The bias ratio is a concrete metric that detects valuation bias or deliberate price manipulation of portfolio assets by a manager of a hedge fund, mutual fund or similar investment vehicle, without requiring disclosure (transparency) of the actual holdings. This metric measures abnormalities in the distribution of returns that indicate the presence of bias in subjective pricing. The formulation of the Bias Ratio stems from an insight into the behavior of asset managers as they address the expectations of investors with the valuation of assets that determine their performance.