Fintech companies have high regulatory requirements and require a secure, auditable yet fast solution. Serialized provides strong consistency to your system, while you can maintain fast distribution of information and keep an audit trail of who did what.
Event sourcing provides a single source of truth. Serialized lets you easily rebuild your system state to any point in time to answer any questions regarding what happened.
Money matters. In the finance industry there is no doubt that you need a strongly consistent solution. Aggregates allow for fast and consistent event storage while allowing downstream services to use eventual consistency via projections or event feed subscriptions to catch up.