Not a direct answer, but the plot.xts
function that comes with the xts
package is not fully developed.
You're much better off using plot.zoo
or plot.xts
from the xtsExtra package (which was written as a Google Summer of Code project with the intention being to roll it into the xts package)
Either of these will work:
plot(as.zoo(MKS.L$MKS.L.Close))
text(as.Date('2012-01-01'),y=500,"wobble", cex=4)
#install.packages("xtsExtra", repos="http://r-forge.r-project.org")
xtsExtra::plot.xts(MKS.L$MKS.L.Close)
text(as.Date('2012-01-01'),y=500,"wobble", cex=4)