Can someone explain to me why this higher dividends would lower the number of bonds to sell short in a call replicating portfolio?
this is a tough one. here’s my thinking but i’m not super confident on it: higher dividends --> larger drop in stock price on ex-dividend date --> lower delta (because numerator is smaller while denominator is unchanged) --> fewer long shares in call replicating portfolio --> fewer short bonds in call replicating portfolio
There is a carry benefit when owning a dividend paying stock (cash flow from dividend). However with derivative instruments, you would not receive the same cash flow benefit even though you are still long the stock through a call option. That value needs to be adjusted. Recall the carry benefit adjusted BSM Model to replicate a call:
c = Se–γTN(d1) – e–rTXN(d2)
The continuous yield (γ) has a negative impact on the stock portion of the equation so an increase in the dividend yield would result in a lower call value, keeping the bond portion constant. So to maintain the call value, the bond portion would also have to decrease.
Hope this helps.