A source told MLB.com that the final details have not been completed in the contract.
Harper, 26, hit .249 with 34 home runs and 100 RBIs in 159 games last season for the Washington Nationals. The No. 1 overall pick in the 2010 MLB June Amateur Draft has spent his entire career in Washington. Harper is a career .279 hitter with 184 career long balls. He is a six-time All-Star and was the 2015 National League MVP.
The signing comes a week after former Los Angeles Dodgers slugger Manny Machado signed a 10-year, $300 million pact with the San Diego Padres, representing the biggest free-agent contract in American sports history for a player signing with a new team.