How Weekly Stock Data Relates to Daily Prices
Summary
The document explains why weekly stock-price records can differ from daily records carrying the same date. The question compares Yahoo Finance daily and weekly observations for Exxon and GE, noting discrepancies across reported fields. One reply proposes that weekly values may be averages assigned to an earlier date, but a later answer corrects that interpretation.
The accepted clarification describes the weekly record as covering the week beginning on its displayed date: the open corresponds to the first trading day, while the close and adjusted close correspond to the end of that week. High, low, and volume likewise represent the weekly period rather than a single day's observation. Thus, comparing a weekly row directly with the daily row bearing the same date compares different time intervals. The examples support this explanation, though the discussion concerns Yahoo's displayed data and does not establish how every vendor aggregates or labels weekly bars.
Key ideas
- A weekly price row represents a trading week that begins on its displayed date.
- The weekly open comes from the start of the period, while the close reflects its end.
- Weekly and daily rows with the same date refer to different observation periods.
- The document corrects an earlier suggestion that the weekly value is an average.
- Data conventions may vary across providers, so vendor definitions matter.
Tags
Full text
# Difference in weekly and monthly data # 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 ## Answer by vikram (score 0, accepted) https://quant.stackexchange.com/a/14839 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. ## Answer by Patrick (score 3) https://quant.stackexchange.com/a/65716 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.
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