Watch the 6/9 Chord online guitar lesson by Fareed Haque from 1-2-3 Bossa Nova
By far the most common major chord sound in the bossa nova is the 6/9 chord. There are multiple places to play this voicing on the guitar, and happily all of them use the same fingering, same shape - weird but true. Keep in mind that this voicing has 1, 3, 5, 6, and 9 but usually no 7th. The 7th is dissonant against the root so it's often left out. Since 3, 6 and 9 are all 4ths apart they have a smooth, modern sound with very little dissonance and are usually stacked on top of each other, in 4ths, to bring out that fourthy sound.