The C-sharp major sixth-ninth chord (abbreviated "C#6/9 chord") is a five-note chord consisting of the notes C♯, E♯, G♯, A♯, and D♯. The chord is formed by adding a major sixth and a major ninth to a C-sharp major chord.
C-sharp major sixth-ninth chord
C♯ E♯ G♯ A♯ D♯
1 3 5 6 9
pentad (five-note chord)