* Wave of mergers fuelled by shift away from cash
* Deal values Worldpay at about $43 bln including debt
* Worldpay shareholders to get $112.12 per share
* Cash-and-stock deal offers premium of about 14 pct (Adds quotes from source close to deal, adds analyst comment)
By Justin George Varghese, Rachel Armstrong and Pamela Barbaglia
March 18 (Reuters) - U.S. fintech Fidelity National Information Services Inc (FIS) has agreed to buy payment processor Worldpay for about $35 billion, the biggest deal to date in the fast-growing electronic payments industry.
The deal is part of a wave of consolidation in the financial technology sector as firms seek to bulk up on payment systems that are increasingly used for online and high street sales.
"Scale matters in our rapidly changing industry," said FIS Chief Executive Officer Gary Norcross, who will lead the combined group that will be a global powerhouse in providing the infrastructure for banking and payment systems.
Global payments are set to reach $3 trillion a year in revenue by 2023, according to consulting firm McKinsey, as more people switch from cash to digital payments.
"This was an opportunistic move by FIS and was primarily triggered by the need to stay ahead of competitors," said a source close to the deal.
The industry's growth has kept deals for payment systems rolling even as merger moves in other sectors have stalled on concerns about trade tensions and a global slowdown.
U.S.-based Fiserv Inc bought payment processor First Data Corp in January for $22 billion, while Italy's Nexi plans to list in what could be one of Europe's biggest initial public offerings (IPOs) this year.
The FIS deal, valuing Worldpay at about $43 billion when debt is included, comes a little more than a year after U.S. firm Vantiv paid $10.63 billion for the payments firm, which was set up in Britain and spun off from Royal Bank of Scotland in 2010.
"Vantiv had yet to realise all the synergies from the Worldpay merger but FIS's offer was too good to be refused," the source close to the deal said.
FIS and Worldpay combined will have annual revenue of about $12 billion and adjusted core earnings of about $5 billion.
"By acquiring Worldpay, FIS should accelerate its revenue growth, significantly expand its position in the merchant acquiring space and generate many synergies," said Michael Schaefer, portfolio manager at Union Investment, a Worldpay shareholder.
Worldpay is a major player in card payments, particularly in Britain, while FIS focuses on retail and institutional banking, as well as payments.
"You need scale to win at payments processing and this deal certainly gives the two companies incredible breadth of coverage," said Russ Mould, investment director at AJ Bell.
Worldpay shareholders will receive 0.9287 FIS shares and $11 in cash for each share held, valuing the company at $112.12 per share, a premium of about 14 percent based on the stocks' Friday closing, according to Reuters calculations.
Shares in Worldpay, which has provided payment processing services for more than 40 years, were up 10.5 percent at $108.99 and Fidelity's shares were up 2.2 percent at $111.25 in premarket trading on Monday.
The companies said the deal would result in an organic revenue growth outlook of 6 to 9 percent through 2021, and $700 million of total core earnings savings over the next three years.
The companies said they expected $500 million of revenue savings and aimed to deliver nearly $4.5 billion of free cash flow in three years.
Under the deal, shareholders will own about 53 percent in the combined firm and Worldpay shareholders about 47 percent.
Worldpay's CEO Charles Drucker will become the executive vice-chairman.
FIS, which has grown through a series of acquisitions in the past 15 years, offering software and outsourcing services banks, asset managers and insurers.
Centerview Partners and Goldman Sachs were financial advisers to FIS, the companies said, adding that Willkie Farr & Gallagher LLP served as FIS' legal adviser in the transaction. (Additional reporting by Arathy S Nair, Simon Jessop Editing by Saumyadeb Chakrabarty and Edmund Blair)