Under Armour previously completed a deal to become MLB's uniform supplier in 2020.
Nike will reportedly become Major League Baseball's uniform supplier instead of Under Armour, according to Sports Business Daily.
In 2016, Under Armour completed a deal with MLB to supply all on-field jerseys beginning in 2020. As part of the deal, Fanatics would also become the league's apparel retailer.
The deal between MLB and Nike is 80% complete and expected to be announced around the All-Star Game in July, reports Sports Business Daily.
By not going through with the deal, Under Armour will save around $50 million and reduce overhead as the company has been struggling.
"They were a different company when they did the deal," a source told Sports Business Daily. "It's just not affordable for Under Armour anymore."
Under Armour currently makes some cleats, compression sleeves, batting gloves and catchers' gear for MLB.
VF's Majestic Athletic has supplied MLB's jerseys since 2005 and will continue to do so through the 2019 season.