Original sentence: Stepping through the data, the bottom axis shows various call options which an investor could write (AKA sell or short).The plot does not show the portfolio value of each of the options on the same day, instead the plot is showing the portfolio value at expiry
Edited sentence: It is worth noting that the plot does not show the portfolio value of each of the options on the same day, instead the plot is showing the portfolio value at expiry.Steping through the data, the bottom axis shows various call options which an investor could write ( AKA sell or short)