Sales                   prices based on MOPS plus premium   

                            Prices should lag spot prices due to manufacturing time

Purchases          costs based on spot prices...costs increase in rising crude prices environment

Opening stock     In rising prices environment, openiing sock creates stock profit because of cheaper cost of manfacturing

closing stock        This should be lower of cost and net realisable values.. Profits are not recognised until products are sold.

Gross margin.......You  can see from the above, there are  opposing forces at work....in a rising price environment, opening stock                               creates a better margin, while feedstock price increases ....is this adeuately compensated by higher selling                                        prices?   depends on MOPS prices and premiums , and there is a lagging effect.

I hope this helps......There are opposing forces at work, and depends on manufacturing cycle, lagging effects, opening stock prices.....and level of opening stocks. .

It is not a simple straightforward case as some of you have been misled to believe.