Apple, Nvidia, and Palantir Technologies are not the only stocks that have been amazing performers for investors. Even some banking stocks have soared in recent years -- like SoFi Technologies (SOFI 7.12%).

Just how much has SoFi Technologies soared by? Well, if you'd invested $1,000 in it three years ago, your stake would be worth around $3,824 as of Aug. 21. That's an average annual gain of 56% -- versus, for comparison, a still-respectable 17% for the S&P 500 index.

SoFi especially targets younger customers. Image source: Getty Images.

Meet SoFi Technologies

Returns like that may have you eager to invest in SoFi Technologies, yourself. Before getting into whether you should, it's worth getting to know the company.

In its own words, SoFi says:

SoFi's mission is to help people reach financial independence to realize their ambitions.

And financial independence doesn't just mean being rich -- it means getting to a point where your money works for the life you want to live.

Everything we do is geared toward helping our members get their money right. We're constantly innovating and building ways to give our members what they need to make that happen.

That's all kind of vague, though, right? So know that SoFi is an online bank -- a "fintech" business -- that also offers personal finance services. In its early days it focused more on student loan services, but now it also encompasses auto loan refinancing, personal loans, mortgages, credit cards, investments, and, of course, banking. It especially targets millennials and other youngish consumers, and it serves them via an app and its website.

SoFi Technologies is aiming to be a one-stop shop to its nearly 12 million members. It recently boasted $73 billion-plus in funded loans and more than $34 billion in debt paid off by members.

Its "SoFi Plus Premium" membership program offers lots of perks that add up to more than $1,000 in annual value, per the company. These benefits include an unlimited 1% match in its SoFi Invest service, unlimited (and free) one-on-one appointments with financial planners, 3% back on hotels via its SoFi Travel portal, up to 3.3% cash back rewards on its credit card, and more. This membership costs $10 per month -- or less.

Should you invest in SoFi Technologies?

So -- should you invest in this exciting stock? Well, maybe. Since it's growing briskly, it can reasonably support a steeper valuation, but its recent price-to-sales ratio of 9 is quite steep, as is its recent forward-looking price-to-earnings (P/E) ratio of 69. My colleague Matt Frankel has recently noted: "At the current share price, SoFi trades for about 4.1 times book value, a hefty premium to pay for a bank. For context, Bank of America currently commands a valuation of about 1.3 times book, while JPMorgan Chase, which is generally considered an 'expensive' bank stock, has a price-to-book valuation of 2.4."

In such a situation, you might play it safe and just add SoFi to your watchlist, waiting and hoping for a better, lower price. Or you might buy into the stock incrementally over time. Or just jump in -- but you'll fare best with that approach if you aim to hang on for many years, so that you'll have time for the stock to recover if it falls.

Do dig into the stock more, to see how much of a rosy future you see for the company. You might check out a Motley Fool Research report that found that around three quarters of banking customers are likely to switch banks if they find something they like better. That bodes well for SoFi as long as it makes itself attractive via offering many services. SoFi is already adding millions of new customers annually.

SoFi Technologies' recently reported second quarter was solid, with membership growing 34% year over year to 11.7 million members and adjusted net revenue up 44% to $858 million. One highlight was the growth in fee-based revenue, up 72% to $378 million.

SoFi Technology is executing its strategies well and its future is very promising, with a lot of growth potential. Its shares aren't cheap, but they're worth consideration for your portfolio.