The Miami Marlins and slugger Giancarlo Stanton are closing in on what could be a record contract extension worth $300 million, according to sources that spoke to ESPN reporter Buster Olney.

Stanton is considered to be one of the best hitters in the game and after years of trade speculation, it appears that the Marlins are prepared to sign him to a megadeal. According to ESPN.com, the Marlins and Stanton have been talking about a deal for some time and it could be in the range of $300 million dollars, which would be the richest of all-time.

Ken Rosenthal at Fox Sports is reporting that the deal could be worth up to $320 million and in the 12-year range for Stanton. Stanton hit .288 last season with 37 home runs and a .555 slugging percentage and he finished in second place in the MVP voting in the NL. Stanton may have taken the MVP had he been able to finish the season, but he was hit in the face with a ball late in the year and was shut down the rest of the way by the Marlins.

Miami finished out of last place in the division for the first time in three years and now Stanton could be the centerpiece as the team tries to build a winner. The Marlins have Jose Fernandez and they are coming back after a 77-85 season. Stanton has 154 home runs already and is just 25 years old and currently he will be a free agent after the 2016 season. Stanton's new deal could rival Miguel Cabrera, who has a deal for ten years and $292 million.