so what makes a company a target for activist investors? what are various steps a company can do to avoid being a target? Are shares still held by the founder

so what makes a company a target for activist investors? what are various steps a company can do to avoid being a target? Are shares still held by the founder an important factor? Is it realistic for the founder to hold shares looking that far down the road for the day an activist investor starts evaluating their company as a target? When activist investor look at Amazon, is the number of shares personally held by Bezos a relevant factor to their analysis?