Hyundai and sister brand Kia jointly invested $84 million in the electric startup in 2019 to take a 12 percent stake.
Hyundai subsequently announced two projects: an electric sports car for Hyundai's N performance subbrand and a sporty fuel-cell vehicle.
It is unclear whether the Korean company will sell its stake in Rimac.
Hyundai has not yet replied to a request for comment.
Hyundai's relationship with Rimac soured as the Croatian company became more closely linked to Porsche, according to one source.
Last year Porsche increased its stake in Rimac to 24 percent, up from 10 percent.
At same time, Rimac formed a 55-45 joint venture with Porsche to take over Volkswagen Group's Bugatti hypercar brand.
Hyundai will finish the electric sports car project started in collaboration with Rimac in-house, one of the sources said. The vehicle's expected launch date is early 2023.
Joint work on the fuel cell project, previewed by the Hyundai Vision FK concept shown last year, won't continue, the sources said.
"We have two active high-level projects ongoing [with Hyundai], one completed and several future projects under discussion," a Rimac spokeswoman said in an email reply to questions from Automotive News Europe.
The company didn't say whether the completed project was the electric sports car.
Rimac denied Porsche's increased influence in the company had caused a rift with Hyundai.
"Hyundai has been supportive in the transformation of the company during the last 12 months -- including the carve-out of Rimac Technology and joining forces with Bugatti under the new company Bugatti Rimac," The spokesperson said.
Rimac has positioned itself as a supplier of performance components for electrified cars under the leadership of entrepreneur and founder Mate Rimac, including supplying the drivetrain for the Pininfarina Battista hypercar.
Rimac also makes its own electric supercars, the latest being the Nevera, which is schedule to reach customers this year. The Nevera will be limited to 150 units.
Mate Rimac said last year he understood that his company's growth might harm relationships with its shareholders.
"The stakes are getting bigger," he told Bloomberg.
"But I am not somebody to play it safe. Never. Not even close. So, if there is going to be some friction with our shareholders and more experienced people that come into the company, it's going to be that."
Mate Rimac told Automotive News Europe in February that despite equity investment from the likes of Porsche and Hyundai, Rimac was still not fully established. "We are not over the edge or out of the Death Valley of companies yet," he said.