sa_final=0
series <- read.csv("path", sep="t", dec=",")

for (i in 2:k){
   y <- ts(series[,i], frequency=12)
   y[!is.finite(y)] <- 0

   #some calculations
   ....
   #trying to merge all time series
   time <-seq.Date(from=as.Date("2001-01-01"), by="months", length.out = n )
   sa <- xts(y, order.by=time)
   sa_final <- cbind(sa_final, sa)
}