@Imhilli So for ipo,fpo etc preopen session is from 9 to 9:45 am. 9:45 to 10 is order matching, and after that trading starts. For general stocks the preopen is 9 to 9:08 am. 9:08 to 9,15 is order matching and after that trading. So for 45 min for ipo(or 8 min time for all other stocks) you can modify,place,reject the orders. And you are right, the price starts changing after 9:30 only because thats the time big players jump in to catch the participants off guard(as you know in preopen, to certainly buy ,you need to put in higher prices>listing price, but catch is reqd higher margin, hence people tend to put in prices just by some points difference, similarly for sell. Here is where wild volatility in preopen can reject buy/sell orders of normal people).
9 to 9,30 the buy/sell orders are like sloth. Normal stocks are also same, after 9,05 only the major volume come in. And as i said Previously, at just 9,43 am the orders vanish, so logically these should be algo fake buy/sell orders to manipulate listing price. I have seen this in wilmar.
Sorry for long message. But if company is good and you know that listing price discovery is very less than what it deserves then you could jump it in. Thats what i did in usk, but because of t2t i also wanted to mitigate risk so used less capital.
These preopen are very helpful in news based pumps/dumps. One could buy/short in preopne and make quick bucks if news are just longterm beneficial and no change in short term. Cheers. Happy weekend