A minor 9th chord is created by adding a 9th degree to any minor7th chord. For example, a Cm9 chord contains the notes C, Eb, G, Bb and D (1, b3, 5, b7 and 9). Here are some common open minor 9th chord shapes.
Cm9

Dm9

Em9

Fm9

Dbm9

Ebm9

F#m9

Gm9

Abm9

Am9

Bbm9

Bm9
