Calculating Weekly Returns from Daily Time Series of Prices v2 - vba

Question

This is a slightly adjusted version of the question here: Calculating Weekly Returns from Daily Time Series of Prices which was answered by #Scott Craner:
I want to calculate weekly returns of a mutual fund from a time series of daily prices. My data looks like this:
A B C D E
DATE WEEK W.DAY MF.PRICE WEEKLY RETURN
02/01/12 1 1 2,7587 -0,0108
03/01/12 1 2 2,7667
04/01/12 1 3 2,7892
05/01/12 1 4 2,7666
06/01/12 1 5 2,7391
09/01/12 2 1 2,7288 0,0067
10/01/12 2 2 2,6707
11/01/12 2 3 2,7044
12/01/12 2 4 2,7183
13/01/12 2 5 2,7619
16/01/12 3 1 2,7470 0,0511
17/01/12 3 2 2,7878
18/01/12 3 3 2,8156
19/01/12 3 4 2,8310
20/01/12 3 5 2,8760
23/01/12 4 1 2,8875
The date is (dd/mm/yy) format and "," is decimal separator. This would be done by using this formula: (Price for first weekday of next week - Price for first weekday of current week)/(Price for first weekday of current week). For example the return for the first week is (2,7288 - 2,7587)/2,7587 = -0,0108 and for the second is (2,7470 - 2,7288)/2,7288 = 0,0067.
The problem is that the list goes on for a year, and some weeks have less than five working days due to holidays or other reasons. Some weeks start with weekday 2, some end with weekday 3. So I can't simply copy and paste the formula above. I added the extra two columns for week number and week day using WEEKNUM and WEEKDAY functions, thought it might help. I want to automate this with a formula and hope to get a table like this:
WEEK RETURN
1 -0,0108
2 0,0067
3 0,0511
.
.
.
I'm looking for a way to tell excel to "find the prices that correspond to the min weekdays of two consecutive weeks and apply the formula "(Price for first weekday of next week - Price for first weekday of current week)/(Price for first weekday of current week)".
I would appreciate any help! (I have 5 separate worksheets for consecutive years, each with daily prices of 20 mutual funds)

Answer 1

It seems to me that you can generate your column E with this formula in E2 :
=IF(B2=B1, "", (VLOOKUP(1+B2, B3:D9, 3, FALSE) - D2)/D2)
It's a VLookup limited on the next 7 rows from each row that declares a new week.
Copying into all cells will give the result indicated in your first tableau. To transform this result into to the list (Week, Return) is a matter of a filter that hides blanks from E.
Notice that a problem could occur if the WeekNum restarts from one when a new year is reached, but since you say that each of your sheets is for one (calendar) year, it shouldn't happen.