When I buy a stock, I try to remind myself that I am buying a small part of a business and that I intend to hold my stocks for the long term. Warren Buffett famously said that his favorite holding period is forever. While that's aspirational more than anything, it's an important reminder that success in investing comes from identifying great businesses and then letting them compound over decades.

While some stocks in my portfolio have a lot more to prove to stay there forever, there are some that I can't imagine myself selling. These businesses have long track records and competitive advantages that should pave the way for bright futures. As the saying goes, "Never say never." Yet with these stocks, I'm as close to never selling as one can be.

Costco

Every time I am struggling to find parking or waiting in the long (but efficient) line to check out, I ask myself why I don't own more Costco Wholesale (COST -0.98%) stock. While most of my fellow shoppers are likely not having the same thought, we're all there to take advantage of the bulk quantities and low prices. History tells us that this business model has been wildly successful with Costco shares gaining more than 81,000% since its IPO.

Costco ended its fiscal 2024 second quarter (ended February 2024) as the third-largest global retailer and the 12th-largest company in the Fortune 500, with 874 locations worldwide. Its membership model works well. More than 92% of Costco members renew their membership and the company brought in nearly $5 billion in membership fees in the past 12 months.

The low prices keep customers coming in the door, and because Costco sells fewer items than its competitors and turns its inventory over very quickly, it can sometimes even sell items before they need to be paid for. This helps cash flows and reduces expenses.

Amazon

If there's a retailer that comes first to mind for me other than Costco, it has to be Amazon (AMZN -0.03%). I don't think I am alone in finding myself shopping there before almost anywhere else. Over the trailing 12 months, Amazon stock is up 82%. However, during the market slump of 2022, the company fell nearly 50% as it struggled to get its finances back in order following the massive distribution build-out necessitated by the pandemic surge in orders.

Amazon is certainly back on track and ready to reaccelerate its growth. In 2023, Amazon grew revenue by 12% but the more impressive results were further down the income statement. Operating income increased by 202% and net income grew by 1,226%. These results were driven by a recovery in the e-commerce business, which finally turned the corner after its 2022 struggles. It's also worth remembering that Amazon Web Services (AWS) remains the leader in cloud infrastructure and it grew its revenue by 13% in 2023.

Apple

Consumer electronics giant Apple (AAPL 2.56%) has been in the news lately for all the wrong reasons. Finding itself increasingly under the microscope of federal antitrust investigations, the stock has fallen 12% over the past three months. This news is certainly worth watching, but it will take years to play out and the rather modest decline in Apple's share price suggests the market's level of concern is less severe than some of the headlines indicate.

Taking a step back, it's important to remember that Apple is still a ubiquitous brand around the world, and especially within the United States. Known for its iPhone and other consumer electronic devices, Apple is slowly becoming a software company. Apple now has an installed base of more than 2.2 billion devices.

This creates an ecosystem of apps and subscription services that provide a high-margin income stream for the company. In the most recently reported quarter, services revenue (which is where all the subscription products are reported) grew by 11% to $23 billion. This represents 19% of total revenue, up from 18% in the year prior.

Why I'm "never" selling

Are there scenarios in which I might sell these companies? Sure, anything is possible. However, these three businesses are so competitively advantaged and are still growing so impressively at their large scale, that it's difficult to envision a scenario where they wouldn't warrant a spot in my portfolio. Investing can be as simple or as complicated as you want it to be. In my mind, buying and owning these three stocks is about as simple as investing can be.