Margin formula

Hi all

I need a drag down formula in column f of the attached sheet which contains thousands of rows. Col g contains
the ouput which I require. It is the difference between the highest and second highest in the totals column (d) in each race which is defined
by date and time in col a and col b.

thanks

Chester

Thanks Bebo ...I have tried it out on my full sheet and it works fine. I had never heard of The Aggregate function.I have more learning to do!!