As of now, the warrants are exercisable at $4, which means no investor would exercise below $4 plus the original cost of the warrant, which if I believe those involved in the offering recieved one share and one warrant for 4.13.
The warrants we're originally trading at .65 upon the offering on the open market.
Now at .35, any price above 4.35, would put the warrants "in the money".
I'm not sure of any possibility of lowering the exercise price since they were already offered on the open market...I guess I'd need to ask a financial advisor on that one.
As of now, it appears sigma may believe their common stock may reach that $4 mark in the time frame they will need the extra cash, mid to late 2018 by current projections.
A stretch from recent price action....but that's the only conclusion that makes sense as of now.