This was a stunningly successful position: genuinely I wish I had done it.
It also produces a very large taxable gain.
Mr Ackman however has been producing less-than-stellar performance for his Pershing Square fund.
So at the moment he is leaving his clients with large losses plus a large tax bill. I can't imagine they would be thrilled with that.
Logically then Bill Ackman will wipe his taxable gain by reducing or exiting one of his large losing positions - either the short on Herbalife or the long on Valeant.
I really don't have any insight into which - but he is on the board of Valeant and that makes moving the Valeant position more problematic.
PS. This observation is not original. I received similar from at least three separate emails.