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I would assume that day to day movement in stock can be accurately compared with the Adjusted Close Price and not simply the Close Price, taking into account Stock Splits Dividends etc. http://www.investopedia.com/ask/answers/06/adjustedclosingprice.asp

Eg: For INFOSYS (INFY, NSE) https://in.finance.yahoo.com/q/hp?s=INFY.NS&a=11&b=12&c=2002&d=11&e=20&f=2014&g=d

The 2 day SMA (Simple Moving Average) on 19 Dec 2014 is (1998.65 + 1965.90) / 2 = 1982.275 Which is what Yahoo Finance is giving me.

But the 2 Day SMA on 2nd Dec 2014 Should be =

(Adj Closing on 1st Dec + Adj Closing on 2nd Dec ) / 2 = (1087.46 + 2126.60)/2 = 1606.73

But it is infact (According to Y! Finance)

(Closing on 1st Dec + Closing on 2nd Dec ) / 2 = (2174.93 + 2126.60)/2 = 2150.765

So the 2:1 Split has no effect on the SMA? I have taken the example of 2 Day SMA for easy calculation but my question is for general MACD, Bollinger Bands, EMA etc.

Many people seem to point to bugs with Yahoo's implementation. I thought given Yahoo's reputation, I thought this was too far fetched but this almost confirms it

Any known bugs with Yahoo Finance adjusted close data ?

Still one thing remains, should one adjust for these splits manually then for Technical Indicators? If not wouldn't it cause a skew in the results?

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    $\begingroup$ I am not sure how Yahoo or Google finance calculate their technical indicators but I would assume it is based off of the last traded price. For example, if you check out freestockcharts.com they calculate their technical indicators real-time (during normal market hours) based on the last traded price thanks to BATS. I would hope Yahoo corrects for splits etc $\endgroup$
    – Rime
    Commented Dec 22, 2014 at 21:28
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    $\begingroup$ @Rime This is exactly what I mean! I also hoped they adjust for splits (which they do in Adjusted Close price in CSVs) but for Tech indicators apparently they don't! $\endgroup$
    – Gaurav Ramanan
    Commented Dec 23, 2014 at 7:43
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    $\begingroup$ A very warm welcome to QuantSE and thank you for your great question! $\endgroup$
    – vonjd
    Commented Dec 23, 2014 at 8:31
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    $\begingroup$ @vonjd Thank You for your welcome :)! Unfortunately the question has not generated any views, hence the bounty! $\endgroup$
    – Gaurav Ramanan
    Commented Dec 23, 2014 at 8:33
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    $\begingroup$ Whether Y!Finance is wrong is not a matter of opinion. Sometimes it just is wrong as pointed out by vonjd, Matt Wolf and chrisaycock. I believe the important lesson here is: don't rely on the data provided by Yahoo, it might be best but it's not perfect. Satisfaction guaranteed, or your money back. By the way: it seems to me that data quality is not the topic of this question and vonjd deserves his bounty. $\endgroup$
    – Bob Jansen ♦
    Commented Dec 27, 2014 at 10:55

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As can be seen from this example from Yahoo!Finance this should not happen (click on "+ The adjusted close"):
https://help.yahoo.com/kb/finance/SLN2311.html?impressions=true

Another more complete example can be found here:
http://luminouslogic.com/how-to-normalize-historical-data-for-splits-dividends-etc.htm

So my explanation is that this is a glitch in the data... remember: Yahoo!Finance is free and they sometimes don't have the highest quality!

An alternative would be Google Finance but they don't provide adjusted data at all. Yet from these data here it can be seen that it must be a glitch in the Yahoo adjusted data:
https://www.google.com/finance/historical?q=NSE%3AINFY&ei=FCmZVPH9OeeqwAPf_IGwBg

Another helpful discussion on this issue can be found here: Daily returns using adjusted close

To answer the question whether a manual adjustment should be made: You should always make an apples to apples comparison. If that requires manual intervention: so be it.

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    $\begingroup$ I hope you agree with the sub-answer on the new sub-question. As it's small and off-topic stand alone I don't want to create a new question. $\endgroup$
    – Bob Jansen ♦
    Commented Dec 23, 2014 at 15:02

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