Shemya is a granddaughter of Gr.1 Prix de Diane heroine Shemaka, descending from a line that traces to Aga Khan foundation mare Pale Ale.

Shemya was sold as a winning three-year-old filly at the 2014 Arqana Breeding Stock Sale, where she made €160,000 from Blandford Bloodstock. The second foal she produced, Cormorant, sold for 1,050,000 guineas to M V Magnier at Tattersalls Book 1 Yearling Sale, and went on to be a Group winner.

Like Cormorant, Portfolio Duration was bred out of Shemya by Michael Wates. Sold as a yearling to Mike Ryan as agent for Klaravich Stables, she won the Gr.1 New York Stakes in June 2026, defeating Aga Khan runner Cankoura by a head.