Downloading a Batch of Returns Using Yahoo! Finance

I use Google Analytics to track traffic on this site, and I’ve found that the two previous posts on downloading return data from Yahoo! Finance are relatively popular.  For this reason, I’m posting some updated R code which can be used to download returns for a batch of stocks or funds.

My first post on this topic included R code for downloading monthly or weekly returns from Yahoo! Finance, and I created a short video tutorial to demonstrate the code. My second post provided a Google Docs spreadsheet which can be used to download monthly returns.

In this post, I’ve updated the original R code to allow monthly returns for multiple stocks or funds to be downloaded into a single CSV file. This is useful if you want to compare factor loadings for multiple funds, or if you simply want to get the monthly returns for all the funds in your portfolio.

The code uses an input file “funds.csv” which is a list of tickers symbols for the target stocks or funds.  An example file is available here.

The monthly returns are recorded in a file called “fundreturns.csv” which is stored in R’s working directory

Note that I believe Yahoo! Finance limits the amount of data that you can download from the site in a given period of time.  I don’t know the specific rules, but if you put a large number of tickers into the CSV file you might find that the downloads start failing and you’ll have to wait for some period of time before they start working again.

The R code is posted below.  The variable “startdate” should be set to a date a few days prior to the start of the first month for which you want to get return data.  For example, if the first monthly return you are targeting is January 2006, then you can set the start date to “12-25-2005”.  If the start date chosen is earlier than the earliest available price history for some funds, then there could be some misalignment between returns and dates in the output file, so be sure to choose a date which is compatible with available price history for the all the stocks and funds in your list.

R Code:

This code requires both the “tseries” and “zoo” packages to be installed.  For details on installing packages on your specific platform please see the R project documentation on package installation.

# Batch Fund Download
# calcinv: 09/19/2013

# Import tseries and zoo libraries
library(zoo)
library(tseries)

# Uncomment the setInternet2 line if a proxy is required
# setInternet2(TRUE)

# Set Start Date
startdate = "2005-12-25"

# Load CSV file into R
testfunds <- read.table("funds.csv",sep=";",header=FALSE)

# Extract tickers and fund weights
ticks <- testfunds[,1]

# Setup Equity Fund Variables
funds <- NULL

# Download equity fund data
for(i in 1:length(ticks)){
# Download Adjusted Price Series from Yahoo! Finance
prices <- get.hist.quote(ticks[i], quote="Adj", start=startdate, retclass="zoo")

# Convert daily closing prices to monthly closing prices
monthly.prices <- aggregate(prices, as.yearmon, tail, 1)

# Convert selected monthly prices into monthly returns to run regression
r <- diff(log(monthly.prices))  # convert prices to log returns
r1 <- exp(r)-1                  # back to simple returns

# Now shift out of zoo object into ordinary matrix
rj <- coredata(r1)

# Put fund returns into matrix
funds <- cbind(funds, rj)
}

fundfile <- cbind(as.character(index(r1)),funds)
header <- c("Dates",as.character(ticks))
fundfile <- rbind(header,fundfile)

# Write output data to csv file
write.table(fundfile, file="fundreturns.csv", sep=",", row.names=FALSE,col.names=FALSE)