Calculating a stock's percent change - Aussie Stock Forums

# Thread: Calculating a stock's percent change

1. ## Calculating a stock's percent change

When it is said that a stock, index, or other moved 8% (or any other per cent), how does one calculate this manually, what is the formula?

Thank you

2. ## Re: Calculating a stocks per cent change

Originally Posted by tom82
When it is said that a stock, index, or other moved 8% (or any other per cent), how does one calculate this manually, what is the formula?

Thank you
Difference divided by the previous, then all multiplied by 100
((\$current-\$previous)/\$previous)*100

e.g. ((\$108-\$100)/\$100)*100

3. ## Re: Calculating a stocks per cent change

Originally Posted by burglar
Difference divided by the previous, then all multiplied by 100
((\$current-\$previous)/\$previous)*100

e.g. ((\$108-\$100)/\$100)*100
Thanks very much, appreciated! That's a great start.

The only problem is I get a different answer to what the broker or asx says the per cent move was.

4. ## Re: Calculating a stocks per cent change

Originally Posted by tom82
Thanks very much, appreciated! That's a great start.

The only problem is I get a different answer to what the broker or asx says the per cent move was.
what numbers are you using? open and close? or previous close and todays close?

5. ## Re: Calculating a stocks per cent change

Originally Posted by db94
what numbers are you using? open and close? or previous close and todays close?
I was using Last and Open.
I was using PVD as an example.
http://asx.com.au/asx/research/compa...de&asxCode=PVD
It seems the ASX and brokers don't give both the open and close prices, unless they call them something else, am I missing something?

6. ## Re: Calculating a stocks per cent change

Originally Posted by tom82
I was using Last and Open.
Use yesterday's close and today's Last price (or close).

7. ## Re: Calculating a stocks per cent change

Originally Posted by Gringotts Bank
Use yesterday's close and today's Last price (or close).
Thanks for that, I will try that.

- - - Updated - - -

Originally Posted by tom82
I was using Last and Open.
I was using PVD as an example.
http://asx.com.au/asx/research/compa...de&asxCode=PVD
It seems the ASX and brokers don't give both the open and close prices, unless they call them something else, am I missing something?
I mean for previous days close.

8. ## Re: Calculating a stocks per cent change

Originally Posted by Gringotts Bank
Use yesterday's close and today's Last price (or close).
This is how it is done. How'd you go?

Just ran a few calcs and I got the same numbers as the ASX website.

Screen Shot 2013-09-02 at 9.13.01 PM.png

Heres how I did it:

29th August, last price = 0.64 (this becomes youre yesterdays close) lets call it pc (previous close)
30th August, last price = 0.67 (this becomes youre current price) let call it cp

therefore: ((cp-pc)/pc) * 100= % change
((0.67-0.64)/0.64) *100 = 4.69% as per asx

9. ## Re: Calculating a stocks per cent change

Originally Posted by db94
This is how it is done. How'd you go?

Just ran a few calcs and I got the same numbers as the ASX website.

Screen Shot 2013-09-02 at 9.13.01 PM.png

Heres how I did it:

29th August, last price = 0.64 (this becomes youre yesterdays close) lets call it pc (previous close)
30th August, last price = 0.67 (this becomes youre current price) let call it cp

therefore: ((cp-pc)/pc) * 100= % change
((0.67-0.64)/0.64) *100 = 4.69% as per asx
That's interesting because I get 4.6875 not 4.69, are you rounding it up?

I did do a another calculation today and got similar result to the above and the asx site (are they rounding as well?):
Last
02 Sep 2013 0.730 8.96%
30 Aug 2013 0.670 4.69%

((0.73-0.67)/0.67 * 100= 8.955%

10. ## Re: Calculating a stocks per cent change

They (the ASX) should have the previous days close at the top of the page where they have Last, %, Bid, Offer, High, Low, Volume.
The same with brokers they should have the Open/Close on the top of the quote page instead of having to go searching through historical data, at least the last five days would be a start.
If the same info is available through charts, like candle stick charts that's ok I guess.

11. ## Re: Calculating a stocks per cent change

Originally Posted by tom82
They (the ASX) should have the previous days close at the top of the page ...
If they made it that easy, everyone would get rich!

12. ## Re: Calculating a stocks per cent change

Originally Posted by burglar
If they made it that easy, everyone would get rich!
I think that is sarcasm, no? I think there is more to trading than the open/close prices and one can not possibly trade just off this information alone.

13. ## Re: Calculating a stock's percent change

The arithmetic daily return is expressed as

( Close[today] - Close[yesterday] ) / Close[yesterday]

This is generally acceptable for simple non-quantitative use, and does not differ much from the geometric daily return except for large numbers.

If you are using the return for anything mathematical, it is definitely advised to use the geometric daily return.

http://en.wikipedia.org/wiki/Rate_of_return

It's very important to understand the difference between the arithmetic and geometric return!

http://cssanalytics.wordpress.com/20...pound-returns/

14. ## Re: Calculating a stocks per cent change

Originally Posted by tom82
I think that is sarcasm, no? I think there is more to trading than the open/close prices and one can not possibly trade just off this information alone.
Sarcasm is the lowest form of wit.
As I am the light entertainment in this forum, I give myself permission for a little levity.

Did the emoticon give me away?

15. ## Re: Calculating a stocks per cent change

Originally Posted by burglar
Sarcasm is the lowest form of wit.
As I am the light entertainment in this forum, I give myself permission for a little levity.

Did the emoticon give me away?
or it is the last refuge of a scoundrel

PS: the method of calculation seems to be rather similar to that suggested in the percentage difference in NTA/Shareprice for LIC/ETF and the same thread starter as well. Hmm, Mrs Watts my Grade 6 teacher would have been most disappointed.

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