Kosta Peric, deputy director of digital payments and financial services for the poor at the Bill & Melinda Gates Foundation, discusses his efforts to expand access to low-cost financial services in developing countries. Peric, who joined the foundation in 2013 after more than two decades at Swift,  also talks about creating interoperability between mobile money systems across borders; the foundation’s answer to the challenges of AML and KYC; why bitcoin doesn't fit the bill yet; and more.