R/05_coveredCall.R

In bullishTrader: Bullish Trading Strategies Through Graphs

#'Calculates Profit and Loss (PnL) per share (or unit of the underlying) and Breakeven (BE) point at expiration for Covered Call and draws its graph in the Plots tab.
#'@description
#'This strategy is also known as buy-write strategy that results from buying stock and writing a call option with a strike price X against the stock position. The outlook of trader or investor on the stock price is neutral to bullish. The covered call strategy has the same payoff as writing a put option (short/naked put). While maintaining the long stock position, the trader can generate income by periodically selling OTM call options (Kakushadze & Serur, 2018).
#'@details
#'According to conceptual details given by Cohen (2015), and a closed form solution provided by Kakushadze and Serur (2018), this method is developed, and the given examples are created, to compute per share Profit and Loss at expiration and Breakeven (BE) point for Covered Call and draws its graph in the Plots tab.
#'@param ST Spot Price at time T.
#'@param S0 Initial Stock Price
#'@param X Strike Price or eXercise price.
#'@param C Call Premium received on shorted call.
#'@param hl lower bound value for setting lower limit of X axis displaying spot price.
#'@param hu upper bound value for setting upper limit of X axis displaying spot price.
#'@param xlab X axis label.
#'@param ylab Y axis label.
#'@param main Title of the Graph.
#'@param sub Subtitle of the Graph.
#'@return returns a profit and loss graph of Covered Call.
#'@importFrom graphics abline
#'@importFrom graphics points
#'@importFrom graphics text
#'@importFrom graphics lines
#'@importFrom graphics par
#'@importFrom graphics plot
#'@importFrom graphics legend
#'@importFrom graphics axis
#'@author MaheshP Kumar, \email{maheshparamjitkumar@@gmail.com}
#'@references
#'Cohen, G. (2015). The Bible of Options Strategies (2nd ed.). Pearson Technology Group.\cr
#'Kakushadze, Z., & Serur, J. A. (2018, August 17). 151 Trading Strategies. Palgrave Macmillan. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3247865
#'@examples
#'coveredCall(17,17,1.44,15.84)
#'coveredCall(50,50,4,48,hl=0.7,hu=1.2)
#'coveredCall(1000,1000,10,990,hl=0.97,hu=1.02)
#'@export
coveredCall <- function (ST,X,C,S0,hl=0,hu=1.5,xlab="Spot Price ($) on Expiration",ylab="Profit / Loss [ PnL ] at Expiration ($)",main="Covered Call ", sub="bullishTrader / MaheshP Kumar"){
  myData <- data.frame (spot = c((ST*hl):(ST*hu)))
  myData$pl <- (myData$spot-S0)-pmax((myData$spot-X),0)+C
  oldpar <- par(no.readonly = TRUE)
  on.exit(par(oldpar))
  myData$pl = round(myData$pl, digits=2)
  myData$spot = round(myData$spot, digits=2)
  par(mfrow = c(1,1), bg="azure1",las=1,mai=c(1.12, 0.92, 0.82, 0.82))
  plot(myData$spot, myData$pl, pch=21, bg="cyan1",col="cyan1", xlab = xlab, ylab = ylab,col.lab="springgreen4", cex.lab= 1.1, main = main,col.main="violetred", col.sub="lightsteelblue2", sub=sub,cex.sub=0.8,xaxt="n")
  text (myData$spot, myData$pl, labels = as.character(myData$pl), adj=-0.25,
        pos = NULL, offset = 0.3, vfont = NULL,
        cex = 0.5, col = "red", font = NULL )
  points(x=(S0-C), y=0,cex = 2, pch = 23, col ="red",bg="gold")
  text((S0-C),1, labels=(S0-C), adj = 0.1,col="goldenrod3")
  abline(h = 0,col = "gray")
  abline(v = X,col = "gray",lty=5,lwd=1.25)
  legend("topleft", legend = c("PnL Point","BE Point"),text.col ="snow",  bg ="darkorchid4", pch=c(16,18), col=c("cyan1","gold"),cex = 1)
  lines(myData$spot,myData$pl,col = "blue")
  axis(4, at=myData$pl,labels=myData$pl, col.axis="red", las=2,cex.axis=0.8,col.ticks ="lightsteelblue2")
  axis(1, at=myData$spot,labels=myData$spot,col.axis="blue",las=1,cex.axis=0.7,col.ticks = "lavenderblush2")
}