River Markets, which gives professional traders a single place to trade across multiple prediction markets, raised an $8.5M seed led by Haun Ventures (Camila Grigera Naón/Fortune)

River Markets is positioning itself as a broker for prediction markets, offering professional traders a single point of access rather than requiring separate accounts on each platform. By centralising order entry, pricing data, and settlement reporting, the service aims to streamline the workflow for institutions that treat these markets as financial instruments. The seed funding will likely be used to onboard additional market venues and to develop the back-end infrastructure needed for real-time aggregation. The engineering implications are immediate: any system that integrates River Markets must handle multiple market APIs, each with its own authentication, data schema, and latency profile. Building adapters that translate a unified order format into the native calls of each underlying market will be a core development task. Moreover, the platform will need to reconcile differing settlement cycles and payout calculations, which adds complexity to risk-management modules. From a cost perspective, the primary expense for adopters will be the development resources required to integrate with River Markets' API and to maintain compatibility as new markets are added. While the fundi