# Difference in weekly and monthly data

I am confused about the following: I checked daily and weekly prices for Exxon (and also GE). But the values for Open, Low, High, Close, Vol., Adj. Close for both data streams seem to differ from each other.

Example (Exxon financial data via Finance Yahoo):

---Date ----------------- Close -------------- Close

Jan.19.1970 ----- 60.25 (weekly) ----- 61.87 (daily)

or

Sep.18.2014 ----- 95.78 (weekly) ----- 97.77 (daily)

On the eye it seems that the only value which is the same in both data streams is Open price.

Why is this? Normally I would suggest that it should be possible to convert a daily dataset into a monthly dataset.

Hope anyone can help to solve the confusion.

Cheers Peter

If you look at the image above you will find data for Exonn mobile. The first 10 rows are daily data and below that is weekly data. I have calculated the weekly price for daily closing values. The red coloured cell is the average for the brownish cells, which is similar to the green cell (weekly price from yahoo finance).

So they have taken average price for the next next 4 days (after 6th) and assigned that value to the first date (6th). I do not thing it is the right way to do.

I would suggest you to download the daily price and make further changes in it, rather than using weekly data from Yahoo finance or let it be any source.

• Very interesting. This makes no sense to me why Yahoo is doing this. Wonder if other data providers do the same!? And what is the intention of this? Would be very happy to hear other opinions? Sep 24, 2014 at 11:16
• This is just the process of defining a week. I am fine with their defining of the week if they are consistent with one definition. Mostly during analysis depending on the characteristic of the variable, by characteristic I mean stock/flow, aggregate figures are defined average or last value. Hence, I prefer to deal with daily values and defining aggregate figures as per my requirement, rather than using theirs. It would be problematic if they change the definition later. Sep 24, 2014 at 12:42

If anyone else is wondering what the actual answer is, I've figured it out. When viewing as weekly or monthly data, yahoo displays the Open, Low, High, Close, Vol., and Adj. Close "as of the end of the week/month beginning on ____." It is not an average of any kind.

Using OP's example, Exxon opened at 60.25 on Jan 19, 1970 and closed at the end of the week at 60.25 on Jan 23, 1970. It closed at 61.87 on Jan 19. Hence the difference between daily and weekly.

---Date ----------------- Close -------------- Close

Jan.19.1970 ----- 60.25 (weekly) ----- 61.87 (daily)

We can see this in vikram's answer as well. The weekly data for the week beginning Jan 6 2014 opens at 99.94 and closes at 100.52 with and adjusted close of 98.45. The daily data shows the same with Jan 6 opening at 99.94, and Jan 10 closing at 100.52 with and adjusted close of 98.45.

• I think this is the common way of going from higher to lower frequency for price data. Jun 25, 2021 at 20:52