What does MTF stand for?

Could you please clarify for me what does the acronym "MTF" represent? I've been encountering it quite frequently in my readings about cryptocurrency and finance, but I'm not quite sure of its exact meaning. It seems to be an important term in this field, and I'd appreciate it if you could shed some light on its significance and usage. Is it related to a specific type of trading strategy, a financial instrument, or perhaps a regulatory framework? Thank you for your assistance in clarifying this matter for me.