“the warrants are $2.73 so they indicate $4.75 as fair value for the shares”

That’s only true if the warrants were expiring today (implying very little premium). They are not so the price differential will be greater.

The value of a warrant is composed of two components, the part that is in the money and the part that is the premium.

The amount in the money is the price of the stock minus the strike price.

Premium is what you pay for the right to convert into shares at the strike. This is more valuable the longer the period of time to expiry.

Imagine a warrant set to expire today and it’s almost end of day and the stock is very stable, then the fair price for the warrant will be equal to the ‘in the money’ amount.

 Now imagine a warrant with infinite time to expiry and a strike price equal to the current stock price, the fair value of the warrant is certainly above zero, because if it was zero or close to it one could sell shares and buy a lot of warrants and have much more upside and exactly the same downside.

Therefore there is always a price to be paid for the premium and the premium is correlated with time to expiry and the market’s anticipation of the possible paths the stocks’ price will take during that time.

Premium explains why fair value of the stock is always greater than warrant price plus strike price.