You probably already know that Avengers: Endgame doesn't have a typical postcredits stinger and may have wondered why it breaks that Marvel Cinematic Universe tradition.

Directing duo Anthony and Joe Russo revealed why in a USA Today interview on Wednesday.

"It was never in the cards," said Joe. "It was called 'Endgame' for a reason. This is it. This is the ending. The book is closed on that chapter of the Marvel universe and a new book will get written."

In closing that book, they chose to include what Anthony called "an echo of the past" -- the clanging sound of Tony Stark (Robert Downey Jr.) building his first Iron Man armor from the 2008 movie that kicked off the MCU.

The Russos leapt in to direct 2014's Captain America: The Winter Soldier. They then took the lead on Captain America: Civil War and Avengers: Infinity War before reaching the Endgame.

"This was the first Marvel movie we've done where we weren't thinking about the future," Anthony told USA Today.

The Russos might not have to think about the future, but Marvel Studios sure do -- Phase 4 begins after Spider-Man: Far From Home swings into theaters in July.

First published at 3:34 a.m. PT.
Updated at 3:58 a.m. PT: Adds more details.