Building a stock portfolio from scratch can be a challenge. There are thousands of stocks to choose from, and most of them won't outperform the major stock market indexes. However, by choosing a diversified set of stocks with solid fundamentals, savvy investors can build a portfolio that not only survives but thrives.

Below, I'll discuss how I would construct a hypothetical portfolio today if I had $50,000 to invest.

A glass jar full of $100 bills on a wooden table.

Image source: Getty Images.

Visa

To get things started, I'm turning to Visa (V -1.06%). The company's business model is one of my favorites within the entire stock market because of its simplicity and asset-light nature. Moreover, it benefits from an enormous network effect that keeps growing stronger every year.

Visa partners with card-issuing institutions (e.g., banks and credit unions). Those institutions provide debit and credit cards to their members, and the cards are used to perform transactions across Visa's payment network. In exchange for access to the payment network, the company collects fees on each transaction, which is how it generates the bulk of its $37 billion in annual revenue.

All told, it processes around 234 billion transactions per year with a staggering value of $16 trillion. For comparison, that value of transactions is roughly equal to the entire gross domestic product (GDP) of either China or the European Union.

For my hypothetical portfolio, I'll allocate $20,000, or 40%, to this stalwart of the financial industry.

Robinhood Markets

The online brokerage industry is nothing new. Investors have been able to place orders and track investments there for at least 30 years now.

However, Robinhood (HOOD 2.96%) is by far the fastest-growing major brokerage firm. According to research by The Motley Fool, Robinhood ranks ninth in assets under management (AUM), with around $100 billion, as of the end of 2023.

It easily takes first place when it comes to the speed at which it's growing its AUM. As of the end of 2023, its AUM growth rate stood at 96%, blowing away its next closest competitor, Ally Financial, with 47% growth.

Much of this is due to Robinhood's popularity among younger investors, who are drawn to the company's focus on crypto, futures, and live-event trading. Moreover, the company looks well placed to benefit from the Great Wealth Transfer, as trillions of dollars in investment-related accounts pass from baby boomers to their heirs.

For my hypothetical portfolio, I'll allocate $5,000, or 10%, to Robinhood.

Meta Platforms

Lastly, there's Meta Platforms (META 0.85%). Simply put, Meta's fundamentals are too good to ignore. For example, over the last 12 months, here are some of the key figures the company has reported:

Over the last five years, those figures increased by 127%, 183%, and 178%, respectively. By comparison, Home Depot, which generates roughly the same amount of annual revenue as Meta, grew revenue and net income by only 34% and 25%, respectively. Home Depot's free cash flow also fell by 7% over the last five years.

Meta's fundamentals are growing shockingly fast for a company of its size. That's the power of scale, and it's a power that Meta wields, thanks to its global user base. The company has nearly 3.5 billion daily active users, so it can generate a staggering amount of advertising revenue.

Furthermore, buy-and-hold investors should be rewarded for years to come, thanks to the company's strong free cash flow and fortress balance sheet. Although Meta only pays a meager dividend right now, the company will likely gradually increase it over the long run.

For my hypothetical portfolio, I'll allocate $25,000, or 50%, to Meta to round out my $50,000 investment pool.