Does a negative alpha automatically mean I should sell?

Investors and analysts use numerous technical indicators to assess the relative risk associated with a given stock. Optimal risk management involves assessing an investment's risk and profitability potential from all angles, including its performance relative to that of the broader market. Consistent underperformance may be an indicator of limited growth potential or inefficient business practices.

One of the most popular metrics for comparing a company's performance to that of the wider market is alpha. In its essence, alpha reflects the degree to which a stock's returns meet or exceed the returns generated by the market. A stock with an alpha of zero performs in line with the market. A positive alpha indicates the security is outperforming the market, while a negative alpha indicates the security fails to generate returns at the same rate as the broader sector. By definition, a stock with a negative alpha is underperforming, but does this mean you should sell as soon as this metric dips below zero?

Consistent underperformance can be a huge red flag. However, by using market returns as the baseline for performance evaluation, alpha assumes that the risk level of the individual security, called company-specific risk, is comparable to that of the market, called systematic risk. For this reason, alpha is more useful in the context of portfolio analysis because the distribution of investment capital over several different securities allows for diversification. Optimal diversification can completely negate company-specific risk, making the overall risk of the portfolio equal to the risk of the market. Because this kind of diversification is impossible with single-security investments, alpha is a less accurate reflection of performance.

Alpha is just one metric that should be analyzed when creating an investment strategy. As with any other indicator, it is important to take a comprehensive view of an investment's relative risk rather than basing decisions on one value alone. In single-security investments, a negative alpha isn't necessarily a signal to sell if the security is still generating returns. In portfolio management, a negative alpha indicates that your investments aren't optimally diversified.