A long-term mindset is one of the most important qualities any investor can possess. In most cases, life-changing wealth doesn't accumulate overnight. Instead, it takes time for compounding to work its magic, but that doesn't mean the process is complicated. All you need is patience and a diversified portfolio of high-quality stocks.

SoFi Technologies (SOFI -3.95%) and Upstart Holdings (UPST -8.09%) participate in the unstoppable fintech industry, and both stocks have the potential to grow tenfold in value over the next decade. Here's what you should know.

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1. SoFi Technologies

SoFi is a mobile-first fintech company. Its platform includes lending products like student loans and mortgages as well as financial services like money management accounts (SoFi Money), brokerage services (SoFi Invest), credit cards (SoFi Credit Card), and access to third-party insurance products (SoFi Protect).

In 2020, SoFi also acquired Galileo, a technology platform that allows financial companies to provision digital banking services. For instance, Galileo makes it possible to issue physical or digital debit cards, create deposit accounts, and process payments. Several well-known fintechs rely on Galileo, including Chime, MoneyLion, and Robinhood Markets (HOOD -5.58%).

The breadth and simplicity of SoFi's platform gives it an edge over many other rivals, and that has helped the company grow quickly. In fact, SoFi's member base has accelerated for eight consecutive quarters, and the number of products used by those members has grown even faster. Collectively, that tremendous engagement drove revenue of $231 million, up 101%.

Going forward, SoFi puts its market opportunity at $2 trillion, meaning it has plenty of room to grow its business. To that end, in March 2021, the company submitted its application to become a bank holding company, and it entered into an agreement to acquire Golden Pacific Bank. Once SoFi has a national bank charter, the resultant synergies should supercharge its business.

The company currently relies on bank partners to provide money management services to SoFi Money account holders. But with a bank charter, SoFi could provide those services directly. In turn, that would allow it to fund loans with customer deposits, meaning lower interest rates for borrowers and higher interest rates for SoFi Money account holders. That would not only create value for members, but it would improve the unit economics for SoFi. That's why this stock (with an $18 billion market cap) could grow tenfold over the next decade, becoming a $180 billion company.

2. Upstart Holdings

Upstart is fintech company that's disrupting the consumer lending industry. Traditionally, banks have used credit models that incorporate (at most) 30 variables to determine who qualifies for financing and at what interest rate. However, Upstart believes those models deny many creditworthy borrowers, and that many people who are approved are charged too much. Case in point: 80% of Americans have never defaulted on a loan, but just 48% have access to prime credit.

To that end, Upstart leans on artificial intelligence to make consumer financing more inclusive and efficient. Its platform collects over 1,600 data points per applicant, and measures those variables against 10.5 million repayment events. That allows Upstart to quantify risk more precisely than alternative methods. In fact, the company believes its AI models are four to eight times more effective than traditional credit models.

Who does that benefit? Everybody. Consumers benefit from greater approval rates and lower interest rates, while Upstart's bank partners benefit from greater approval rates (more business) and lower loss rates. And the network effect created by Upstart's AI models should reinforce those benefits over time. In other words, as its platform is used to originate more loans, Upstart will collect more data, making its predictive engine more intelligent.

Not surprisingly, Upstart is growing at a phenomenal pace. During the second quarter, bank partners originated $2.8 billion in loans using its technology, up 1,605% from the prior year. That caused revenue to skyrocket 1,018% to $194 million, and the company posted a profit according to generally accepted accounting principles (GAAP) of $37 million.

Shareholders have plenty of reasons to be excited about this company. Upstart recently entered the auto lending space, bumping its market opportunity to $719 billion, but the company plans to pursue other markets the future, including credit cards, student loans, and mortgages. That would boost its total addressable market (TAM) to $4.2 trillion. To put that in perspective, Upstart facilitated just $4.5 billion in loans through the first half 2021 (or $9 billion on an annualized basis), which represents 1.2% of its current TAM, and 0.2% of its potential TAM.

That's why I think this $26 billion fintech stock can grow tenfold over the next 10 years.