Creating a trademark portfolio is the act of creating several trademarks that protect similar, or distinct, areas of a business. When large companies are evaluating their portfolio, it is frequently siloing different types of related businesses. Think of it like Disney, ABC, ESPN, Marvel, and Star Wars. These are all trademarks of one company that do different things.
For smaller companies, the focus is on protecting different elements of the brand. If the name is different then the domain name, or if the logo doesn’t contain any literal elements (words), a second or additional trademark can protect a new element of the business.
All told, protecting a business through trademarks is focused on protecting each important way a customer can find out about your bruises and identify your offered goods and services.