New Zealand accounting software giant Xero agreed to buy New York payments provider Melio for $2.5 billion, the companies said on Wednesday, accelerating the Kiwi firm's push into the U.S. with the country's biggest outbound deal in over a decade.

The Australia-listed accounting-software provider Xero will partly fund the largest acquisition in its 19-year history with a $1.2 billion institutional placement.

Xero Ltd (ASX:XRO), the New Zealand-based cloud accounting software provider, announced a $2.5 billion acquisition of U.S.-based payments processor Melio Ltd. The binding agreement includes both cash and equity,