Ken Fisher acknowledges that many investors, even professionals, have an investing size and/or style they favor. Large cap. Small cap. Small value. Mid-growth. Maybe they are more specific — only investing in large Tech firms. Small Midwestern banks. Mid-cap Consumer Discretionary, but only if they are value and German.
Money managers and mutual funds often offer "products" adhering to strict size and/or style guidelines. And Ken Fisher notes there is nothing wrong with that. That is how the institutional world functions and has for decades. Except, typically, institutional clients will ensure they have exposure to essentially all the major styles and sizes (growth and value in small, mid, and large cap, domestic and foreign, and all the standard sectors). When institutions do that, they typically either do these slices passively or hire what they consider to be best-of-breed portfolio managers in each category. But many individual investors, even professionals, mistakenly think their favored size and/or style is tops — the best for all time — and will continue being best going forward. And they invest solely or mostly in that particular size/style/category. Ken Fisher explains - A major mistake!
Read more about investing sizes and styles in BUNK 10 of Ken Fisher's Debunkery.