par(mar=c(2, 2, 1, 1))
par(mfrow=c(2, 1), xpd=NA)

plot(datasets::EuStockMarkets[,"DAX"], type="l", axes=FALSE,
     xlab="", ylab="", main="")
box(col="gray")
mtext("Mid 1991", adj=0, side=3)
lines(x=c(1995, 1995, 1996, 1996), 
      y=c(-1000, 6000, 6000, -1000), 
      lwd=3, col="gray")
mtext("DAX", side=2, line=0)

plot(datasets::EuStockMarkets[,"FTSE"], type="l", axes=FALSE,
     xlab="", ylab="", main="")
box(col="gray")
mtext("Mid 1998", adj=1, side=3)
mtext("1995", at=1995.5, side=1)
lines(x=c(1995, 1995, 1996, 1996), 
      y=c(7000, 2500, 2500, 7000), 
      lwd=3, col="gray")
mtext("FTSE", side=2, line=0)