Equinox is out of Chateau Blanche (King Halo), a group winner in Japan who took the Gr.3 Mermaid S. over 2000 metres in 2015. All four of her runners have won, among them the Group 3 winner Weiss Meteor (King Kamehameha) and the triple winner Miss Bianca (Lord Kanaloa). Chateau Blanche is a half-sister to Win Floraison (Fuji Kiseki), dam of the Listed-placed Studley (Harbinger).

Second dam Blancherie (Tony Bin) won twice over 1800 metres and has three other winners, Chateau Blanche the best of her four. She is a half-sister to Blandices (Sakura Bakushin O), a multiple stakes winner over jumps.

Third dam Maison Blanche (Alleged) was Listed-placed and produced four other winners, among them the Listed-placed Osumi Schnell (Sunday Silence) and Blandices. Her half-brother Balleroy (Kaldoun), later a sire, won the Gr.3 Prix de Guiche and was second in the Gr.1 Prix Jean Prat.

The fourth dam is Blanche Reine (Nureyev).

Chateau Blanche has the 2-year-old filly Garza Blanca (Kizuna), a winner on debut, and she foaled a full-sister to Equinox on 26 February.