library(survival)

dm01 <- read.table("dm01ret.dat",header=F,sep="")
names(dm01) <- c("caldt", "S01", "S02", "S10", "S12", "S13", "S14", "S15", 
                  "S16", "S17", "S20", "S21", "S22", "S23", "S24", "S25")

dm02 <- read.table("dm02ret.dat",header=F,sep="")
names(dm02) <- c("caldt", "S26", "S27", "S28", "S29", "S30", "S31", "S32",
                  "S33", "S34", "S35", "S36", "S37", "S38", "S39", "S40", 
		  "S41", "S42", "S44", "S45", "S46", "S47", "S48", "S49",
                  "S50")
dm02 <- cbind(dm02[,1:20],dm02[,22:25])

dm03 <- read.table("dm03ret.dat",header=F,sep="")
names(dm03) <- c("caldt", "S51", "S52", "S53", "S54", "S55", "S56", "S57",
                 "S58", "S59", "S60", "S61", "S62", "S63", "S64", "S65", 
		 "S67", "S70", "S72", "S73", "S75", "S78", "S79", "S80", 
		 "S82", "S89")


stock <- merge(x=dm01, y=dm02, by.x="caldt", by.y="caldt", all=TRUE)
stock <- merge(x=stock, y=dm03, by.x="caldt", by.y="caldt", all=TRUE)

rm(dm01, dm02, dm03)