Swedish mobile POS company iZettle has grabbed American Express as an investor, adding Amex to its recently announced Series B round of funding. Previously announced investors in that round include Greylock Partners, Northzone, MasterCard, and SEB Private Equity, as well as returning Series A investors Index Ventures and Creandum.

IZettle did not disclose the value of the American Express investment but the funds are in addition to the €25 million ($31 million) that was previously announced. Including Series A funding, iZettle has raised around €39 million ($50 million).

The company said it will use the money on product development and expanding its services to new markets.

"The payments landscape is changing rapidly and we believe iZettle's solution will play an important role in helping to further enable commerce — especially in small-merchant segments that have historically relied on cash — by delivering a smart and convenient way for small businesses to accept consumer payments," said Werner Decker, SVP for merchant services Europe at American Express.

Like other mobile POS solutions, iZettle turns iPhone and Android smartphones into payment terminals simply by using a mini chip-card reader and a mobile app. The company is currently offering services in Nordic countries and running tests in the U.K.

According to iZettle, its solution has increased the number of POS terminals in Nordic countries by 10 percent since it began operations last August. 

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