share price if cemex bid is knocked back

Interesting to compare the share price movements of two companies over the last two months.
RIN was sitting on $14 when Cemex made a bid for the company. James Hardie was sitting on $7.50.
Both companies are highly exposed to the US housing market. The only differance is that one is about to be takenover the other isn't.
RIN now stands at $18 - an increase of 28% and JHX is at $9 - an increase of 20%.
Theoretically, then if Cemex were to withdraw it's bid the share price would only fall back 8% ie assuming RIN would have grown at 20% like JHX.
The price then for RIN if the Cemex bid were withdrawn would be $16.66.
Amazing!!!
In otherwords it would be virtually the same as the offer price with a change in exchange rates factored in.