Can someone please help me understand the relationship between periodicity and YTM and periodicity and PV for Discount and Premium bonds?
Is it the following?
For discount bonds - As periodicity increases PV decreases
For premium bonds - As periodicity increases PV increases
As periodicity increases YTM decreases irrespective of premium/discount bond. ( I had read somewhere that for a premium bond as periodicity increases, YTM increases but I’m unsure)
Yes, as periodicity increases, the nominal YTM will decrease. The higher the periodicity, the greater the effect of the magic of compounding.
I have never heard about the relationship for discount/premium bonds. As a test, let’s try a discount bond ( 5year annual pay, 2% coupon, 5% YTM)
P/Y=C/Y=1 (annual coupon, compounding frequency =1)
5 N 5 I PMT 2 FV 100 CPT PV -87.01157
P/Y=1, C/Y=365 (annual coupon, compounding frequency =365)
5 N 5 I PMT 2 FV 100 CPT PV -86.51011
Looks like the discount bond relationship holds. 
Now let’s try a premium bond (5 year annual pay, 10% coupon, 5% YTM):
P/Y=C/Y=1 (annual coupon, compounding frequency =1)
5 N 5 I PMT 10 FV 100 CPT PV -121.64738
P/Y=1, C/Y=365 (annual coupon, compounding frequency =365)
5 N 5 I PMT 10 FV 100 CPT PV -121.0249
It doesn’t look like the hypothesized premium bond relationship holds. 
Thanks for the answer!
For premium bond I think you missed that the coupon is 10 not 2!
Fixed, thanks!!!