Few companies have a true monopoly in any market. More common are "virtual monopolies" or "near-monopolies" that exist due to geography or brand recognition. When consumers hear the term monopoly, the first thing that comes to mind is often price-fixing and other illegal business practices. We are not accusing the companies we reviewed of any wrongdoing.
At one time, Forbes kept a Monopoly Index, but it only required for companies to have 50% or more in market share to be included. Virtual monopolies or monopolies in the making don't have that kind of market power, but they are plenty powerful. Investors would be advised to consider the ones reviewed by 24/7 Wall St.