The stock market has been hammered recently, and technology stocks have been hit harder than most. In fact, the technology sector recently sank into bear market territory, which means it's down more than 20% from its highs.

Fintech stocks haven't been spared from the carnage, but the sell-off has also created some pretty nice buying opportunities. Here's why three of our contributors think Green Dot (NYSE:GDOT), S&P Global (NYSE:SPGI), and Ellie Mae (NYSE:ELLI) are worthy of a closer look as 2018 comes to a close.

"Sale" signs in storefront window.

Image source: Getty Images.

A great way to play the War on Cash

Matt Frankel, CFP (Green Dot): I've written before about Green Dot as a fintech investment that could do particularly well in the so-called War on Cash.

If you aren't familiar, Green Dot's core business is producing banking products for people who don't have traditional bank accounts or credit cards. For example, its prepaid debit cards can be found for sale at major retailers throughout the U.S., and its GoBank checking account product allows people who can't qualify for a checking account with a traditional bank to do things like write checks, send money through a mobile app, or pay bills online. This area of the business focuses on the subset of the population that is most likely to still rely on cash for day-to-day purchases, so it has tons of potential as we transition to a cashless society over the coming decades.

In recent years, Green Dot has focused on building out its "banking as a service" platform, or BaaS. Essentially, Green Dot uses its technology and infrastructure to develop banking products for other companies. For example, Green Dot's technology is behind the Apple Pay Cash person-to-person payment app and Uber's Instant Pay, which allows drivers to get paid for rides right away.

The company has added several high-profile partners in 2018, and I foresee many more partnerships on the horizon. After all, there are lots of companies that could benefit from offering banking products to their customers but that don't necessarily want to become "banks" themselves.

Green Dot has been a victim of the market volatility recently and is currently about 15% off from its 52-week high. So now could be a great time to add this under-the-radar fintech stock to your portfolio.

A low-tech fintech

Jordan Wathen (S&P Global): This company may be very old school, but it has all the traits that make fintech stocks attractive: high margins, low capital requirements, and a long runway for growth over time.

S&P Global's core business is bond ratings, which are to companies what credit scores are to individuals. In exchange for up-front and ongoing fees, S&P Global ascribes a letter grade to debt issued by companies large and small. Roughly 90% of the ratings industry is controlled by just three companies, none of which want to destroy their margins to gain a small amount of market share. In the most recent quarter, the ratings business had an almost unbelievable adjusted operating profit margin of 56.5%!

The data S&P Global collects can be monetized in other ways. Its Market Intelligence and Platts businesses sell data to banks, pension funds, and other major investors on subscription, collecting recurring fee revenue. It also makes money licensing its brand name and indexes to index funds and ETFs. For example, one of the largest S&P 500 ETFs pays S&P Global a fee of $0.03 for every $100 invested in it, just for the right to use the predominant large-cap stock index. More than $1.5 trillion of wealth is invested in an index associated with one of S&P Global's indexes.

After a recent market rout, shares trade for just under 20 times earnings guidance in 2018. That price is more than fair, given that S&P Global's capital-light business affords it the ability to grow with little reinvestment, thus enabling it the freedom to use all of its earnings to pay dividends and buy back stock.

Making mortgages easier -- and more profitable

Dan Caplinger (Ellie Mae): A decade ago, the housing market was in shambles, and millions of homeowners were struggling to make payments on their mortgages. Yet thanks to government programs, low interest rates, and the efforts of policy makers and industry professionals, the housing market has rebounded sharply since the mid- and late 2000s. The ability to refinance mortgages was a key driver of that rebound, and as mortgage lenders saw their financial health improve, they were able to make more loans.

Ellie Mae played an instrumental role in making it possible for more financial institutions to tap into the mortgage market. The financial technology specialist created a platform that mortgage professionals could use to track their efforts throughout the mortgage lending process, starting with pitching prospective customers and moving through the application, origination, servicing, and payoff stages. Over time, Ellie Mae's platform has gained so much acclaim that it's attracted an ever-rising number of financial institutions to join its client base, and those network effects are only adding to Ellie Mae's ability to make further improvements to meet its customers' needs.

Currently, many investors are nervous about the future course of interest rates, and that's put a chill in the mortgage market. Despite fears of an economic downturn that could lead to a pause for the housing market's growth, Ellie Mae will still appeal to those lenders who need to keep tracking existing business. That makes the stock a good prospect, especially after having pulled back more than 40% in the past six months.