The next financial technology megamerger could be on the horizon, but some industry analysts worry the deal being floated might not be the right fit.

Global Payments Inc. is nearing a deal for Total System Services Inc., commonly referred to as TSYS, for about $20 billion, people familiar with the matter told CNBC. The deal is expected to be announced May 28. In an industry where scale is critical to success, major players like Global Payments and TSYS have had to contend with how this year's massive mergers — between Fiserv Inc. and First Data Corp., and Fidelity National Information Services Inc. and Worldpay Inc. — will reshape the landscape.

This combination has been widely contemplated in the market since the tie-ups broke earlier in the year, but Nomura analyst Dan Dolev believes it could be only a "marriage of convenience."

Such a move would "mark a sharp 180-degree turn" in Global Payment's narrative, Dolev said in a May 24 note. Emerging solutions such as Square Inc.'s CashApp, which target the underbanked, are increasingly posing long-term threats, Dolev said. But an acquisition of TSYS would "further entrench" Global Payments in TSYS's payment-centric issuer processing business, merchant acquiring practice and prepaid cards.

Still, after two megamergers announced in the first quarter, "the race is on" to create a third two-sided network platform that serves both merchants and financial institutions, said Wedbush analyst Moshe Katri in a May 24 note. And this combination between two complementary businesses would do just that.

TSYS is the largest third-party processor for credit card issuers in the U.S., servicing about 40% of Visa Inc.'s and Mastercard Inc.'s domestic card accounts in 2018, Katri said. Global Payments is the fifth-largest merchant acquirer in the U.S., according to a March report from the Nilson Report, an industry trade publication.

Neither company responded to requests for comment.

At a recent conference, Philip McHugh, senior executive vice president of merchant solutions at TSYS, suggested that his company cannot sit by as the payments industry shifts to software and cloud-based solutions, PaymentsSource reported at the time.

Consolidation in the payments market has been a hot topic in 2019, and McHugh said there is "no doubt TSYS is part of that conversation." The company's goal is "to go big or go home on the acquiring side," he said at the conference.

But Global Payments is larger than TSYS and is growing "significantly faster," according to MoffettNathanson analyst Lisa Ellis.

The analyst believes Global Payments is "highly likely" to be involved in a transaction sometime in 2019. The anticipation of a potential deal is one of the primary reasons Global Payment's stock is up more than 40% year-to-date, she said in a May 24 note. But the payments company has many M&A options it could pursue.

Global Payments might prioritize using acquisitions to strengthen its merchant-acquiring business. In that case, it would likely try to acquire a brick-and-mortar or omnichannel merchant acquirer outside the U.S., such as Brazil's Cielo SA, Ellis said. Less likely but also possible scenarios see Global Payments targeting an e-commerce-focused merchant acquirer or a mobile point-of-sale provider, she added. It also could continue its acquisitions of vertical-specific software assets.

While a tie-up with TSYS is "possible," another outcome for Global Payments is "equally, if not more, likely," Ellis said.