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Writer's pictureEda Coşkun

Finding Adjusted Daily Returns of Stocks with R

Updated: Sep 23, 2020

You are looking at the Yahoo Finance, monitoring returns of several stocks and think about how can you get the relevant information in this excessive amount of data and make simple but meaningful results from them. Thankfully, R provides you with great tools for manipulating the data for your own interest of use.


In this post, I will download stock data using quantmod and the Yahoo Finance API and manipulate the data using some R sub-setting functions. I will pull down adjusted daily return stock data using Microsoft's and Facebook's stock. Then combine data for comparison. With the combined data, I will practice calculating the Sharp Ratio on multiple stocks to see which stock is truly the riskier asset or the stock with the best risk return profile.


So let's get started


Derive the stock data for Microsoft (MSFT)

MSFT<-getSymbols("MSFT",auto.assign = F)  #getSymbols returns stock data for the variables you choose
## 'getSymbols' currently uses auto.assign=TRUE by default, but will
## use auto.assign=FALSE in 0.5-0. You will still be able to use
## 'loadSymbols' to automatically load data. getOption("getSymbols.env")
## and getOption("getSymbols.auto.assign") will still be checked for
## alternate defaults.
## 
## This message is shown once per session and may be disabled by setting 
## options("getSymbols.warning4.0"=FALSE). See ?getSymbols for details.
head(MSFT)#visualize first 5 rows of data set
##            MSFT.Open MSFT.High MSFT.Low MSFT.Close MSFT.Volume MSFT.Adjusted
## 2007-01-03     29.91     30.25    29.40      29.86    76935100      22.07034
## 2007-01-04     29.70     29.97    29.44      29.81    45774500      22.03338
## 2007-01-05     29.63     29.75    29.45      29.64    44607200      21.90772
## 2007-01-08     29.65     30.10    29.53      29.93    50220200      22.12207
## 2007-01-09     30.00     30.18    29.73      29.96    44636600      22.14425
## 2007-01-10     29.80     29.89    29.43      29.66    55017400      21.92251
tail(MSFT)#visualize last 5 rows of data set
##            MSFT.Open MSFT.High MSFT.Low MSFT.Close MSFT.Volume MSFT.Adjusted
## 2020-08-25    213.10    216.61   213.10     216.47    23043700        216.47
## 2020-08-26    217.88    222.09   217.36     221.15    39600800        221.15
## 2020-08-27    222.89    231.15   219.40     226.58    57602200        226.58
## 2020-08-28    228.18    230.64   226.58     228.91    26292900        228.91
## 2020-08-31    227.00    228.70   224.31     225.53    28774200        225.53
## 2020-09-01    225.51    227.45   224.43     227.27    25725500        227.27
df_MSFT<- as.data.frame(MSFT)

class(MSFT)       #check whether we can store the msft as data frame
## [1] "xts" "zoo"
class(df_MSFT)
## [1] "data.frame"

Derive the stock data for Amazon

AMZN<-getSymbols("AMZN",auto.assign = F)
df_AMZN<- as.data.frame(AMZN)  #store as data frame

str(df_AMZN) #str() allows the user to see what type of object the data frame is.
## 'data.frame':    3441 obs. of  6 variables:
##  $ AMZN.Open    : num  38.7 38.6 38.7 38.2 37.6 ...
##  $ AMZN.High    : num  39.1 39.1 38.8 38.3 38.1 ...
##  $ AMZN.Low     : num  38 38.3 37.6 37.2 37.3 ...
##  $ AMZN.Close   : num  38.7 38.9 38.4 37.5 37.8 ...
##  $ AMZN.Volume  : num  12405100 6318400 6619700 6783000 5703000 ...
##  $ AMZN.Adjusted: num  38.7 38.9 38.4 37.5 37.8 ...
summary(df_AMZN)# statistical summary of numerical variables
##    AMZN.Open         AMZN.High          AMZN.Low         AMZN.Close     
##  Min.   :  35.29   Min.   :  37.07   Min.   :  34.68   Min.   :  35.03  
##  1st Qu.: 131.05   1st Qu.: 132.80   1st Qu.: 129.53   1st Qu.: 131.31  
##  Median : 303.91   Median : 306.21   Median : 300.17   Median : 303.83  
##  Mean   : 630.22   Mean   : 637.00   Mean   : 622.86   Mean   : 630.34  
##  3rd Qu.: 887.50   3rd Qu.: 893.49   3rd Qu.: 884.49   3rd Qu.: 886.54  
##  Max.   :3489.58   Max.   :3513.87   Max.   :3467.00   Max.   :3499.12  
##   AMZN.Volume        AMZN.Adjusted    
##  Min.   :   881300   Min.   :  35.03  
##  1st Qu.:  3086500   1st Qu.: 131.31  
##  Median :  4495100   Median : 303.83  
##  Mean   :  5625767   Mean   : 630.34  
##  3rd Qu.:  6769300   3rd Qu.: 886.54  
##  Max.   :104329200   Max.   :3499.12
head(df_AMZN)
##            AMZN.Open AMZN.High AMZN.Low AMZN.Close AMZN.Volume AMZN.Adjusted
## 2007-01-03     38.68     39.06    38.05      38.70    12405100         38.70
## 2007-01-04     38.59     39.14    38.26      38.90     6318400         38.90
## 2007-01-05     38.72     38.79    37.60      38.37     6619700         38.37
## 2007-01-08     38.22     38.31    37.17      37.50     6783000         37.50
## 2007-01-09     37.60     38.06    37.34      37.78     5703000         37.78
## 2007-01-10     37.49     37.70    37.07      37.15     6527500         37.15

Store the data frame in csv format

write.csv(df_AMZN,file = "amzn stock") 

Find the daily return of the adjusted closing stock price

daily_msft<-dailyReturn(MSFT$MSFT.Adjusted)
head(daily_msft)
##            daily.returns
## 2007-01-03   0.000000000
## 2007-01-04  -0.001674736
## 2007-01-05  -0.005703029
## 2007-01-08   0.009784129
## 2007-01-09   0.001002664
## 2007-01-10  -0.010013388

Visualize the first 10 row (head) the monthly return of the adjusted closing stock price and store as monthly_msft

head(monthlyReturn(MSFT$MSFT.Adjusted),10)
##            monthly.returns
## 2007-01-31     0.033489058
## 2007-02-28    -0.084002434
## 2007-03-30    -0.010649770
## 2007-04-30     0.074273600
## 2007-05-31     0.028370680
## 2007-06-29    -0.039752314
## 2007-07-31    -0.016287909
## 2007-08-31    -0.005495093
## 2007-09-28     0.025409005
## 2007-10-31     0.249491301
monthly_msft<-monthlyReturn(MSFT$MSFT.Adjusted)

Visualize the first 10 row (head) the yearly return of the adjusted closing stock price and store as yearly_msft

head(yearlyReturn(MSFT$MSFT.Adjusted),10)
##            yearly.returns
## 2007-12-31     0.20842884
## 2008-12-31    -0.44385606
## 2009-12-31     0.60467155
## 2010-12-31    -0.06524647
## 2011-12-30    -0.04515672
## 2012-12-31     0.05798857
## 2013-12-31     0.44297966
## 2014-12-31     0.27564613
## 2015-12-31     0.22691902
## 2016-12-30     0.15077722
yearly_msft<-yearlyReturn(MSFT$MSFT.Adjusted)

Plot the daily returns

plot(daily_msft,type = 1)


Adjusted returns step by step

msft_adj<- Ad(MSFT)#take only adjusted returns
msft_adj_daily<-dailyReturn(msft_adj)#store the daily adjusted returns
head(msft_adj_daily)
##            daily.returns
## 2007-01-03   0.000000000
## 2007-01-04  -0.001674736
## 2007-01-05  -0.005703029
## 2007-01-08   0.009784129
## 2007-01-09   0.001002664
## 2007-01-10  -0.010013388
head(daily_msft)#msft_adj_daily and daily_msft are equivalent
##            daily.returns
## 2007-01-03   0.000000000
## 2007-01-04  -0.001674736
## 2007-01-05  -0.005703029
## 2007-01-08   0.009784129
## 2007-01-09   0.001002664
## 2007-01-10  -0.010013388

Finding daily adjusted returns in only one step

new_msft<-dailyReturn(Ad(getSymbols("MSFT",auto.assign = F)))
head(new_msft)
##            daily.returns
## 2007-01-03   0.000000000
## 2007-01-04  -0.001674736
## 2007-01-05  -0.005703029
## 2007-01-08   0.009784129
## 2007-01-09   0.001002664
## 2007-01-10  -0.010013388

Finding the daily return of adjusted closing stock price for Facebook

fb<- getSymbols("FB",auto.assign = F)
fb_ad<- Ad(fb)
fb_daily<- dailyReturn(fb_ad)
head(fb_daily)
##            daily.returns
## 2012-05-18    0.00000000
## 2012-05-21   -0.10986139
## 2012-05-22   -0.08903906
## 2012-05-23    0.03225806
## 2012-05-24    0.03218747
## 2012-05-25   -0.03390854

Finding fb_daily in shorter way

new_fb<-dailyReturn(Ad(getSymbols("FB",auto.assign = F)))

Joining two stocks data sets into one data set

comb_traded<-merge(new_msft,new_fb,all=F)

Rename the column names for better visualization

colnames(comb_traded)
## [1] "daily.returns"   "daily.returns.1"
names(comb_traded)[names(comb_traded) == "daily.returns"] <- "MSFT.returns"
names(comb_traded)[names(comb_traded) == "daily.returns.1"] <- "FB.returns"

Compare the daily returns of Facebook with Microsoft

charts.PerformanceSummary(comb_traded,main="FB-Microsoft")


Annualized Returns and Sharp Ratio

Note! The risk-free rate of return means theoretical rate of return of an investment with zero risk, however, in practice every investment carries at least small amount of risk.

To solve this issue we find an approximate risk-free rate of return, while considering investor’s home market. For example, for U.S. based investors the interest rate on a three-month U.S. Treasury bill is often used as the risk-free rate.

table.AnnualizedReturns(comb_traded,scale = 252,Rf= .004/252)#RF is risk-free rate
##                             MSFT.returns FB.returns
## Annualized Return                 0.3079     0.2802
## Annualized Std Dev                0.2595     0.3741
## Annualized Sharpe (Rf=0.4%)       1.1661     0.7353

Std dev is standard deviation which is a measure of dispersion relative to its mean. It is the square root of variance (volatility)


Sharp ratio is the average return earned in excess of the risk-free rate per unit of volatility or total risk


Generally, the greater the value of the Sharpe ratio, the more attractive the risk-adjusted return.


So as a result, it is shown that Microsoft has higher sharpe ratio which makes it more attractive than Facebook’s stocks


If you want to see this project's R markdown file or find relevant projects, you can go to RPubs and visit edacoskun


The link for this project is

https://rpubs.com/edacoskun/655251


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