optimum size buy/sell blocks of stock?



Newbie question here, I have 900 shares in SWIR and looking at the Nasdaq level 2 screen this morning I noticed the MM was $46.00 bid and $47.29 for 900. The prices for a block of 100 was considerably better at approx. $48+

So my question, if I understand correctly, for selling would I be better off selling 9x100 blocks and paying 9 lots of commission ? And for buying to buy in blocks of 100 rather than say 500/1000 ?

If so presumably there is an optimum balance of price vs commission

Normally I buy/sell through my UK SIPP account and I get offered a price, take it or leave it but since I originally bought stock in approx 100 blocks the price seemed OK
I suspect you looked at prices before the US was open as in the first minute of trading the high was $48.22 and the low $47.86. The prices you saw were ones no-one should trade at in SWIR pre-market.

I don't have the time to explain everything in detail as it would take pages and pages, but your understanding of Nasdaq L2 and trading US stocks and commission charges (the level of which you don't seem aware of) suggests to me that you really shouldn't be trading/investing in American stocks.
You are leaving yourself wide open to your broker screwing you and getting terrible prices.

Please don't be offended by my comments in response to your first post on t2w, it's really about not jumping into the sea when you don't know how to swim.
No offence taken, I've been lucky so far bought in mid $20-$30 in Sept/Oct and nearly at $50 now, hence my question, usually made up the spread in less than a few hours

I did invest in FTSE & AIM originally but not much upside happening so I moved out