The biggest Swiss maker is ETA. There are also a couple of others (Sellita and DD) and some brands make their own movements too.
ETA is cutting down their supplies and we know that Tag is part of the LVMH group which has Zenith (El Primero, Elite movts.) watches too.
Many brands use a ETA base movt. and apply a rotor with their name. Some famous brands also use a base ETA movement and "add"? their own parts too.
This is TAG Caliber 16. Is it 100% Tag-Heuer? (El Primero?) Only in the last 18 months most "famous" brands are naming their movements with their own caliber (before they were happy to state - ie. ETA2824 - Valjoux 7750). Does anyone know what is actually happening, please?