There's one really easy way to improve your investing returns -- lengthen your holding period for the stocks of great businesses. Warren Buffett has long maintained that his "favorite holding period is forever."

Of course, even Buffett sells some of his stocks occasionally. There are some stocks that I own right now that I could envision selling at some point -- but not all of them. Here are three stocks I'm never selling.

$100 bill with a chain and lock.

Image source: Getty Images.

1. Intuitive Surgical

I view Intuitive Surgical (ISRG -2.37%) as one of the best healthcare stocks to buy right now. I also think it's one of the best to hold for decades to come.

Intuitive Surgical offers an ideal 21st-century version of the old razor-and-blades business model. The company sells its robotic surgical systems but makes a lot more money over time supplying replacement instruments and accessories for those systems. Over the last few years, Intuitive has been leasing increasingly more systems as well. This adds up to strong recurring revenue.

The company's robotic surgical systems were used in more than 1.2 million procedures in 2020. Intuitive estimates there are around 6 million procedures performed each year where its technology could be used without any additional regulatory clearances required. And with technological innovations and picking up other clearances, Intuitive's systems could be used in close to 20 million procedures.

Those are current market estimates. With aging populations around the world, the number of surgical procedures performed will increase.

There are other companies with robotic surgical systems on the market. None of them, though, can match Intuitive Surgical's extensive track record of success and its huge install base. 

2. MercadoLibre

I'm convinced that MercadoLibre (MELI -2.80%) is still only in its early stages of growth. This Latin American fintech stock truly has the potential to deliver a 10X return for investors who hold it long enough. 

MercadoLibre ranks as the e-commerce leader in Latin America. The company is also a top online payments processor and logistics services provider in the region. As the middle class expands in Latin America, MercadoLibre should be able to generate impressive growth.

Last year, Latin America was the fastest-growing region in the world for e-commerce. However, even with its rapid growth, the e-commerce market penetration rate remains at only 8%, well below the rate in the U.S. Fidelity International projects that e-commerce penetration could double by 2025 and skyrocket to more than 50% over the next few decades. 

Over the short term, MercadoLibre shares could be volatile. The company's business could be negatively affected if COVID-19 disrupts the Latin American economy or if interest rates increase and put a damper on the economic recovery. Over the long term, though, I fully expect this stock to be a huge winner.

3. Nvidia

I doubt that any futurist would predict that artificial intelligence (AI) and gaming will be less prevalent 20 years from now than they are today. My view is that both arenas will expand dramatically. And that's why I don't plan on selling any of my shares of Nvidia (NVDA 2.63%).

The company's graphics processing units (GPUs) reign as the gold standard for use in data centers that process AI apps and in gaming systems. With Nvidia's continual investment in research and development, I don't see it relinquishing that status.

Nvidia's next big catalyst could come from its self-driving car technology platform. Although self-driving vehicles haven't lived up to the hype so far, I nonetheless think this will be a massive market for Nvidia over the next couple of decades and beyond.

Then there's the metaverse -- a future version of the internet where users can connect in a virtual universe. Nvidia has already developed Omniverse, a platform for virtual collaboration and simulation. Omniverse provides only a taste of what the metaverse could become.

Nvidia CEO Jensen Huang thinks that Omniverse and the metaverse will eventually be "a new economy that is larger than our current economy." If he's anywhere close to being right (and I suspect he is), Nvidia could continue delivering great returns for a long time to come.