Bb Minor Add9, 2nd inversion (E# in the bass)
Also written as Bbmadd9/E#.
Notes, from the bass up
E# (bass)B#A#C#
The same notes as Bb Minor Add9 (E#, B#, A# and C#), rearranged so E# is the lowest note. Use it to move between chords with smaller jumps across the keyboard.