Earlier yesterday you could have sold 4 NOT and bought 17 FWR. NOT was trading up to 1.77, FWR at 0.39. By the close, the discount disappeared, NOT @ 1.61, FWR @ 0.40.

This morning (8:50 am), NOT is indicated @ 1.74 bid/ask, FWR @ 0.40. If the numbers hold on opening, the same discount (or premium, depending how you look at it) could be available. Your downside risk is that the deal could fall through, and FWR goes back to a lower trading range.

Please consider that free opinion is worth what you paid, and do your own d d.