(Adds details on deal, earnings)
LONDON, Aug 9 (Reuters) - U.S. credit card processing company Vantiv moved closer to creating a $29 billion global payments powerhouse on Wednesday with a formal offer to buy Britain's Worldpay for 8 billion pounds ($10 billion).
Although the deal was first announced on July 5, it has taken several weeks of talks to conclude, with the deadline for a formal offer extended twice as the companies haggled over governance and ways to safeguard British jobs.
Worldpay said on Wednesday that Vantiv has offered 55 pence in cash, 0.0672 of a new Vantiv share, an interim dividend of 0.8 pence per Worldpay share and a special 4.2 pence dividend, valuing the former RBS unit at about 8 billion pounds or 397 pence per share.
The combined company will be renamed "Worldpay" and will be headquartered in Cincinnati with a primary listing in New York and a secondary listing in London.
Worldpay shareholders will own approximately 43 percent of the new business, while Vantiv investors will have 57 percent of the combined group whose pro forma enterprise value is more than 22 billion pounds.
The company's international operations will be run from Britain, but there will be no formal guarantees that UK jobs and employees will be protected.
The combined company will be a leading payments firm, processing approximately $1.5 trillion in payments and 40 billion transactions through more than 300 payment methods in 146 countries and 126 currencies, with a combined net revenue of over $3.2 billion.
The group will be led by Vantiv boss Charles Drucker as executive chairman and co-CEO while Worldpay boss Philip Jansen will report to Drucker and act as co-CEO.
Vantiv chief financial officer Stephanie Ferris will retain her role as CFO and report to Drucker.
The combined group will see five Worldpay directors sitting on the board with Sir Mike Rake, who is Worldpay's non-executive chairman, becoming lead director of the new board.
Goldman Sachs and Barclays acted for Worldpay, while Morgan Stanley and Credit Suisse worked with Vantiv on the deal, which gives Worldpay an enterprise value of about 9.3 billion pounds and will result in annual recurring pre-tax cost synergies of about $200 million.
These synergies are expected to be fully realised by the end of the third year following completion of the merger.
But the combined group is also expected to incur one-off restructuring and integration costs of around $330 million.
Craig Bonthron, a fund manager at Kames Capital, told Reuters that the deal was a sensible transaction which allowed UK investors to participate in the upside via a secondary listing in London.
He said the deal will help consolidate "what is a fragmented market and diversify Vantiv's revenues away from struggling 'big box' retailers in the U.S."
Worldpay said on Wednesday its first-half underlying earnings rose 13.6 percent, driven by strong growth across all its businesses and tightened costs at its UK unit.
The company, which had the biggest flotation on the London Stock Exchange in 2015, said underlying earnings before interest, taxes, depreciation and amortization (EBITDA) rose to 247.5 million pounds for the six months ending June 30.
Net revenue rose 17.6 percent to 2.51 billion pounds, with a 2 percent growth in Worldpay's UK business.
Worldpay's e-commerce payment business saw net revenue rise 16.9 percent, driven by contributions from customers including retail, airline and digital industries. ($1 = 0.7699 pounds) (Additional reporting by Arathy Nair and Simon Jessop; Editing by Rachel Armstrong and Alexander Smith)