In a dramatic move that marks an abrupt end of the Big Three era in Boston, the Celtics and Brooklyn Nets agreed in principle to a blockbuster deal that will send Paul Pierce and Kevin Garnett to the Nets, a league source told the Globe Thursday night.

The deal won’t become official until July 10, when a league-wide moratorium on signings and trades is lifted after free agency begins July 1.

But a league source confirmed that Garnett agreed to waive his no-trade clause, meaning the massive deal has cleared perhaps its toughest hurdle.

Though the Celtics will part with two of the franchise’s best and most popular players, the deal represents the front office’s plans to aggressively rebuild the roster. Full story for BostonGlobe.com subscribers.

Baxter Holmes can be reached at baxter.holmes@globe.com. Follow him on Twitter at @BaxterHolmes

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