You can use this code to download end-of-day prices for the stocks in your portfolio. It will write the prices dataframe to a csv file in your working directory. Be sure to change the stock tickers and the from date.

The code requires the quantmod library.

env <- new.env()
Symbols <- c('ECA', 'DDD', 'MO', 'RHT')
getSymbols(Symbols = Symbols, env = env, from = '2015-02-24')
args <- eapply(env = env, FUN = function(x){x[,6]})[Symbols]
prices <- na.omit( = merge, args = args))
colnames(prices) <- Symbols
write.csv(prices, file = "prices.csv")