In one embodiment, a method includes identifying, by a payment service, a plurality of security assets for inclusion in a pack of security assets. A value of the pack of security assets may be determined based on weighted values of a base unit of each of the security assets. Information may be sent to a first user's client device to display a user interface to purchase the pack of security assets. In response to receiving a purchase request in a specified amount, the payment service may calculate, for each of the security assets in the pack, the base units of the security asset based on the respective assigned weight and the value of a base unit of the security asset. Finally, for each of the security assets in the pack, ownership of the calculated number of base units of the security asset may be assigned to the first user.