At Uphold each card in your wallet is given a bitcoin address. This bitcoin address can be used to receive funds directly into the card, and any implied currency conversions are handled for you automatically. For example, when you send bitcoin to a US Dollar card, the bitcoin is first received by our system, then we convert that bitcoin into dollars at the current market rate, and finally add the dollar value of the received bitcoin into dollar card in question. In this scenario funds flow into the card, and that transaction can be found on the blockchain. However, the transactions associated with the currency exchange/conversion may sometimes draw upon funds held elsewhere in our reserve.
