American Express is launching a new online concert series dubbed “Unstaged,” with shows to be streamed live on YouTube and Vevo.

Arcade Fire will kick off the series by live streaming the second of their much-anticipated Aug. 4 and 5 concerts at Madison Square Garden, which follow the release of the band’s third album, “The Suburbs.”

The concert will stream live at 10 p.m. Aug. 5 on the Google Inc.-owned YouTube and Vevo, the music video site owned by Universal Music Group, Sony Music Entertainment and Abu Dhabi Media Co.

It’s the first in a planned series of five live concerts, with John Legend and the Roots to follow, and others later.