think MM is more like a catchall term for anything you cannot classify as a bulge or elite boutique. like hsbc or nomura, like they're definitely not BBs but neither are they boutique. the line is never clear because MM is supposed to suggest smaller (literally middle market) deal sizes on average but some elite boutiques do both megadeals and MM deals. granted HL is often classified as MM but they command so much respect these days i put them on the same level as an elite boutique