F# Major 7#11, 4th inversion (B# in the bass)
Also written as F#maj7#11/B#.
Notes, from the bass up
B# (bass)F#A#C#E#
The same notes as F# Major 7#11 (B#, F#, A#, C# and E#), rearranged so B# is the lowest note. Use it to move between chords with smaller jumps across the keyboard.