Answer: be concentrated in specific industries.
Step-by-step explanation:
Companies that exhibit characteristics such as a high book-to-market ratio and high dividend yield are usually found in specific industries like the financial services sector.
Using this method would therefore lead to investments in specific industries which is riskier because the industrial risk component increases in that if the industry is adversely affected, the investors would suffer from going in on investments concentrated in one or a couple of related industries.