Currently, most market-relevant financial data (e.g. trading volume, lending and banking statistics, companies' ESG impacts, inflation dynamics, etc.) are managed by private proprietors such as Bloomberg, Refinitiv, and NASDAQ, charging a considerable amount of licensing fees for the access and use of those data.
An open-source system, along with allowing low-cost, public access to content, is one whose code or architecture is able to be publicly scrutinized. In finance, it is possible to make such systems highly secure through transparent development and customizable security measures.