A popular variation is replicators, which are tracker themefolios ("TTFs") that combine companies into a cluster that are identified by a common characteristic. This example illustrates the idea behind the Themefolio concept. It shows that a categorization by or to a 'theme' does not always work via an assignment by supersectors, sectors, industries, peer groups, GICS or industry codes. 

One of the most comprehensive, popular and frequently visited TTFs for research purposes is the Hindenburg TTF, which tracks the publications of the research and analysis firm - Hindenburg Research - and compiles the stock market values that are the focus of the company analyses there in a separate TTF.