So, this relates to EOC 10B and 11A from Reading 31
10B - They calculated I/S as being the cost of executing the orders i.e. (Number of shares filled x Cost per share)
11A - I am not even sure about what they have done.
Can someone explain this? Been racking my brains for a while trying to figure this out.
10B is simple because it’s over the course of a trading day with no explicit trading fees and commissions.
11A calculates IS as two parts: the loss from being unable to fill the order (the 50 dollars gain that was lost) and the loss/gain from realized portfolio (real portfolio ending value - real portfolio cost)
if you use the same approach from 11A to 10B, you calculate IS as (30,000 x 53.25) - (10,000 x 53.22 + 10,000 x 53.06 + 10,000 x 52.87) which is equal to 6000.
what may confuse you is that 10B does not restate the IS as a basis point. if restated in bps, the IS is 6000/532500 = 0.0113 or 113 bps.
what confuses me is why use mid-quote as the benchmark price instead of the bid price for 10B since it is a sell order. and for buy order, do we also use mid-quote as benchmark price instead of ask price?
YES!! I was confused about that too. Its a sell order so why not just find the impact of selling on the bid side?
Also, thanks so much for the clarification, this topic really triggered me lol.
ok, so here’s what I think
if benchmark price choice is not mentioned in the question, use mid-quote.
Yea, sounds like what they are implying.