親近性バイアス

Familiarity bias is a cognitive tendency where investors favor well-known assets and avoid unfamiliar investments, even when diversification could improve risk-adjusted returns.

This behavior stems from a fear of change and uncertainty, causing investors to anticipate negative outcomes when considering less familiar options.

For example, John, an investor influenced by familiarity bias, invests only in popular stocks like Apple, Amazon, and Tesla. 

Since these companies are widely recognized, he perceives them as the safest choice. However, when the tech sector declines, his portfolio suffers significant losses. 

In contrast, Sarah, another investor, diversifies across industries such as healthcare, consumer goods, and energy. 

While some of her investments decline, others perform well, stabilizing her portfolio and improving long-term returns.

Familiarity bias can contribute to an unfamiliarity premium, where lesser-known stocks may remain undervalued due to limited investor interest despite strong fundamentals. 

Overcoming this bias fosters diversification, reduces risk, and enhances portfolio resilience against market fluctuations, leading to better financial outcomes.