# Set start and end dates
start = "1990-01-01"
end = "2023-09-09"

df <- new.env()

# Import the data
getSymbols('AAPL',src='yahoo',env = df, from=start,to=end,auto.assign=TRUE)

# Create a dataframe to save the Apple stock adjusted close prices
data <- data.frame(coredata(fortify.zoo(Ad(df[['AAPL']]))))
colnames(data) = c('date','AAPL')

# Compute the log returns for each asset
data$returns <- c(0,log(data$AAPL[-1]/data$AAPL[-length(data$AAPL)]))