Kevin O'Leary of 'Shark Tank' Says This Is One of His Best Investments

Kevin O'Leary of "Shark Tank" says that alternative investment is paying off big time.

Kevin O'Leary

Toilet bowl illuminators. Potato messages. Jarred cupcakes. In his role as one of the “Sharks” on the ABC show “Shark Tank,” Kevin O’Leary makes interesting and quirky investments all the time.

But stocks and start-ups aren’t O’Leary’s only top-performing investments. Another is something he can literally wear on his sleeve: wristwatches.

“I’m always looking at investments,” the business mogul, also known affectionately as “Mr. Wonderful,” tells Grow. “But remarkably, there are plenty of items outside of stocks and bonds that give incredible appreciation.”

“My watch collection…went up almost 50%,” he says.

O’Leary has been a watch collector for more than 30 years and has an extensive collection. How big? He’s reluctant to say—in part because thieves have successfully targeted his watches twice.

“I have it now in three different geographies, so it’s big enough to spread around the world,” he says.

He credits pop culture, along with a number of exclusive and unique pieces, for the growing value of his collection. As an example, O’Leary says that certain Audemars Piguet watches in his collection skyrocketed in value after they “showed up on the arms of a couple of really well-known rappers.”

“Watches have become fashion and style. There’s a certain element of jewelry to them,” he says.

Watches aren’t the only alternative investment that O’Leary counts among his assets. Among other items, he collects musical instruments, wine, cuff links, and pens. Those last two, he says, not only accentuate his outfits but act like a dog whistle to other high-end collectors.

“Those of us that collect pens, watches, and cuff links from specific makers…when we see each other all around the world, it’s a common bond,” he says. “It’s like a secret society.”

For most people, collectibles are not investments

This strategy won’t work for most ordinary people. O’Leary is a multimillionaire with plenty of disposable income. For most people, investing in a diverse mix of low-fee securities and funds is likely the best way to build wealth and focus on big goals like retirement.

Helen Hall, a certified appraiser specializing in entertainment memorabilia, says emotional attachment is what drives many people to buy or invest in collectibles. But buying a collectible because you want to own it doesn’t necessarily make it a good investment. That can be hard to gauge.

“You’ve got to buy wisely,” Hall says. “You don’t know what’s in the market and how the future is going to go.”

A closet full of Beanie Babies, for example, probably hasn’t paid off. O’Leary suggests looking into which collectibles have a high likelihood of appreciating—but warns that there’s always a chance that the market could change. So, don’t be afraid to indulge yourself, sneakerheads. But tread with caution.

“You’re always taking a risk,” he says.

If you do buy a collectible, don’t focus on its potential for appreciation, says Hall. “Buy something that you like and you love,” she says.

Just make sure you have the cash to spend after meeting all your saving and investing goals.

Disclosure: CNBC owns the exclusive off-network cable rights to “Shark Tank.”

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