It's public (technically it has to be in order to be strictly legal for use). But for the most part it is unintuitive, unclean (needs to be heavily normalized)

It's public (technically it has to be in order to be strictly legal for use). But for the most part it is unintuitive, unclean (needs to be heavily normalized) and not easily accessible. There are a variety of vendors that source it, clean it and analyze it to make it salable to firms. Quantitative firms also have teams devoted to doing all of that internally.