Beatles Bible has an intense discussion of how George Harrison (backed by Paul McCartney and John Lennon) played the iconic opening chord from ‘A Hard Day’s Knight’:
The fingering, as played by Harrison on his 12-string Rickenbacker 360/12 guitar, was as follows:
E —-3—-
B —-1—-
G —-2—-
D —-3—-
A —-x—-
E —-x—-The 12-string guitar was crucial to the power of the chord, giving it a richness which would otherwise have been absent. The notes were also used for the arpeggio at the end of the song.
As Harrison pointed out, his 12-string wasn’t the only instrument to be heard during the chord. John Lennon also performed an Fadd9, although on a Gibson J-160 6-string acoustic guitar. Close listening reveals a cymbal and snare drum buried in the mix, and notes performed on the bass and piano.
Paul McCartney added a D note, played on the 12th fret of the D string on his Hofner violin bass. This note was the equivalent of an open D string on a six-string guitar, which had a crucial effect on the overall sound of the chord. The bass note also resonated in the body of Lennon’s acoustic guitar, further changing the sound.
The ‘A Hard Day’s Night’ opening chord
(via Making Light)