I have been investing (softly) in stocks for the last 2 years or so. I am not an experienced stock investor but it seems to me that there is a consensus that some degree of diversification is a safer strategy. Considering that the goal is to balance safety and improve gains, I have been thinking that a better tactic would be:
A) diversity among different sectors/verticals (say retail, technology and utilities) or
B) diversify within a single sector (technology or retail) or even a single sub-sector (say ecommerce websites or infrastructure technology, or brick and mortar retail).
That said, what would be the questions or factors I should weight to define which tactic would be more adequate? Please note that I am not asking for an answer "this tactic", but pointers improve the skill of evaluating strategies.
PS: I searched for previous questions in the diversification or concentration theme here but I could not find an exact match. In general, they tackle diversification vs concentration or talk about diversifying different types of assets and investments.