As per Bailard, Biehl & Kaiser (BB&K) model, the five types of investors are – the adventurer, the celebrity, the Individualist, the guardian and the straight-arrow investor.
There are always people who are so well balanced that they cannot be placed in any specific quadrant, so they fall near the centre; this investor is called a Straight-Arrow investors. On average, this group of investors is a relatively balanced composite of each of the other four investor types, and by implication a group willing to be exposed to medium risk.