The Square Root Of 25

Boston Celtics guard Derrick White has agreed on a four-year, $125.9 million contract extension, sources told ESPN's Adrian Wojnarowski. The deal includes a player option.

Boston acquired White, who turns 30 on Tuesday, at the trade deadline in 2022, sending a first-round pick and a future first-round swap to the San Antonio Spurs to land the versatile guard. White went on to help the Celtics reach the 2022 NBA Finals, where they lost to the Golden State Warriors in six games.

After primarily playing in a sixth-man role down the stretch and in the playoffs for Boston in his first half-season with the Celtics, White moved into the starting lineup for each of the past two seasons, earning second-team All-Defensive honors in each year and establishing himself as one of the league's premier two-way guards.

That reputation was enhanced, in large part, by White making significant gains as a shooter across the past two seasons, hitting 38.1% and 39.6% of his triples in the regular season, respectively, and making more than 40% of them in both of Boston's past two playoff runs. He averaged 13.8 points, 48 rebounds and shot 39.5% from long range in the Finals as the Celtics beat the Dallas Mavericks 4-1 to win the franchise's record 18th NBA title.

By extending White, the Celtics have secured all their core players on long-term contracts as they try to keep the league's defending champions together for the foreseeable future.

ESPN's Tim Bontemps contributed to this report.