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I got stupid lucky with one of my first investments: buying shares of Alphabet (GOOG -1.80%) (GOOGL -1.82%) -- then "Google" -- on March 9, 2009 (the nadir during the Great Recession) for a split-adjusted $150 per share. By the end of the year, shares had doubled.

Upon hearing this, a friend advised, "That's great, but you haven't really gained anything until you sell and have that cash in the bank." Being an investing newbie, I followed his advice...and have missed out on 160% upside ever since.

I'll never let that happen again.

Currently, shares of Alphabet, Amazon (AMZN -1.35%), and Facebook (META -2.28%) make up 44% of my family's real-life holdings. I never intended for it to be this way -- they've all simply grown into those allocations. While some might consider that imprudent, I don't have any intention to sell these three until I need to draw on them for retirement.

That's because they all share three vital characteristics.

1) Financially robust

This might sound like a boring term, but "financially robust" means two things to me: (1) never having to rely too much on one customer for a significant portion of revenue, and (2) having tons of cash on hand and very little debt.

With tens of millions of Amazon Prime customers stateside, I shouldn't need to explain that the company wouldn't be hurt at all if one or two users decided to cancel. The same can be said for Alphabet and Facebook: with millions of advertisers and billions of active users, the effect of just one entity defecting would be barely noticeable.

Just as important, all three are cash cows.

Company

Cash

Debt

Amazon

$18.4 billion

$8.2 billion

Alphabet

$73 billion

$2.0 billion

Facebook

$26 billion

$0

Data source: SEC filings.

In the simplest sense, this means that these companies would be just fine during an economic downturn. And outside of bear economies, all three could potentially buy back tons of shares or even pay dividends should circumstances dictate such a move.

2) Skin in the game

Equally important, I believe that those who run the company have their own interests aligned with mine. Not only are all three run by founders -- who likely have their "soul" in the game -- but they all have management and every day employees who are working toward long-term success. Consider the number of shares and amount of money and control management has in each one.

Company

Management Shares Owned

Approx. Value

Percentage of Voting Control

Amazon

83.4 million shares

$64 billion

17.7%

Alphabet

47.8 million shares 

$37 billion

59.6%

Facebook

546 million shares

$65 billion

61.2%

Data source: Company DEF 14A filings with the SEC.

Making sure that management's long-term goals are aligned with yours is important. But it's equally vital to know that everyday employees -- the ones who actually make the company's mission and vision become reality -- are happy with their company as well.

All three of the companies succeed here, according to reviews on Glassdoor.com

Company

Company Rating (5 is Max)

Would Rec. to Friend

Positive Business Outlook

CEO Approval

Amazon

 3.5  65%  68%  81%

Alphabet

 4.4  91%  83%  98%

Facebook

 4.5  92%  92%  98%

Data Source: Glassdoor.com.

Clearly, Amazon is the laggard of the group. Part of that is due to the fact that it isn't just a technology company per se, but really a logistics and -- increasingly -- delivery service. Those are very different fields.

That being said, I've used Glassdoor as a proxy for employee satisfaction for a long time, and even Amazon's is pretty high.

3) A barbell approach

Best-selling author and trader Nassim Taleb introduced the "Barbell" strategy in his book Antifragile: Things That Gain from Disorder. In essence, this encourages individuals -- and companies -- to take a two-fold approach to the future. On one hand, you should have a very safe and reliable stream of income.

On the other, you should devote a small amount of time to big ideas that only have a small chance of actually panning out. Because only small portions of resources are devoted to such projects, their failure won't cause ruin. In fact, failure is encouraged as it will further an organization's learning.

Amazon may be the best modern-day example of the barbell approach. The company is laser focused on e-commerce on one end, but it's more than willing to experiment and fail on the other. Sometimes, the failures get big headlines (I'm looking at you, Fire phone). But when an experiment really hits (ahem, Amazon Web Services), the effects can be profound.

Google changed its name and corporate structure to make such an approach clear. While it counts on advertising for the bulk of its revenue, it's taking "moonshots", with wild projects coming out of its Google[x] laboratory. And Facebook is famously working on ways to connect the world that include solar drones that can beam Internet access down to remote parts of the world.

Since I plan on holding all three of these for decades, I have little doubt that each will find one or two major successes with this approach -- and I believe the effects will be profound for both the world and our portfolio.

Of course, things can change. If management left from any one of these companies -- or significantly changed their focus -- I would be forced to reevaulate. But as things stand now, I don't see myself selling Amazon, Facebook, or Alphabet...ever.