The market anomaly usually relates to:
- Structural factors, such as unfair competition, lack of market transparency, regulatory actions, etc.
- Behavioral biases by economic agents (see behavioral economics)
- Calendar effects, such as the January effect.
There are anomalies in relation to the economic fundamentals of the equity, technical trading rules, and Economic Calendar events.
Anomalies could be fundamental, technical, or calendar related. Fundamental anomalies include value effect, small-cap effect (low P/E stocks and small cap companies do better than index on an average) and the low-volatility anomaly. Calendar anomalies involve patterns in stock returns from year to year or month to month, while technical anomalies include momentum effect.