So bellingcat is a investigative journalism organization (see their wikipedia for notable cases) that uses open tools and techniques. This article is a guide, written for casual users and journalists, for how to use one such tool.

The key bit is probably:

important area involves investigating company structures and relationships. However, official company registries can be unwieldy or difficult to navigate. This is where OpenCorporates – a free repository of company registries aggregated from primary public sources, published in order to promote corporate transparency – can be helpful. OpenCorporates is clear about the provenance of their data, so you know where they collected each record, and when. This is critical for companies and finance research and investigations.

As for the data (quoted from Wikipedia)

Data is sourced from national business registries in 140 jurisdictions, and presented in a standardised form. Collected data comprises the name of the entity, date of incorporation, registered addresses, and the names of directors. Some data, such as the ownership structure, is contributed by users

So it seems like a one stop shop for data when going down the rabbit hole of the finances for an organization