Baltimore-based sportswear brand Under Armour has extended its ten-year agreement signed in 2015 with US golf star Jordan Spieth to run until 2029.
Spieth's current Under Armour contract pays him eight figures per year.
With a US$29.6 million endorsement portfolio, Sportico listed Spieth as the sixth-best earner in men's golf last year.
Spieth's other sponsors include AT&T, Brightspot, Club Champion, Full Swing, NetJets, Rolex, and Titleist, in addition to Under Armour.
Spieth, who has an estimated net worth of more than US$110 million, has earned more than US$50 million in prize money throughout his career, including his 13th PGA Tour victory at the RBC Heritage. Spieth has also won three major titles: the Masters in 2015, the US Open in 2015, and The Open in 2017.
The 28-year-old golf star will be at least 35 when his apparel contract expires as a result of the current extension. After signing with the brand in 2013, the American has only ever worn Under Armour throughout his career. Spieth has his line of Under Armour golf shoes.