Economic moats are hard-won. After all, it's not easy for a company to establish sustainable competitive advantages that will allow it to earn high returns on capital for years to come.
In addition, moats aren't constant. Once they've been dug, they can erode. Once-strong switching costs could decline due to evolving market trends, for instance. Patents and licenses expire. And new competitors can undercut a company's once-impenetrable cost advantages.
Susan Dziubinski does not own shares in any of the securities mentioned above. Find out about Morningstar's editorial policies.