Like last time, an inelegant solution; but it doesn't use arrays or SQL or anything fancy.

In cell S2 (and down), if this is the close price, display the percentage difference between the opening price and the closing price:
=IFERROR(IF(ROW()=T2,INDIRECT("j"&T2)/INDIRECT("j"&U2),""),"")

In cell T2 (and down), we store the row number of the horse's opening price:
=IFERROR(IF(H2="","",IF(NOT(H2=H1),ROW(),T1)),"")

In cell U2 (and down), we store the row number of the horse's closing price:
=IF(T2=T3,U3,ROW())


So in cells S2 through to U2, it displays the following values:
1.509433962 2 23