Ann: ICI's New Game Claw Stars Early Trial Results, page-532

It has been a long while since I have done much research relating to IPOs but what I used to find is that any sort of anticipation for an IPO can cause a temporary (hopefully) drop in companies in the same sector in the days before and after the IPO as investors (particularly corporate investors) prepare to shift/spread funds into a new company in the sector.

Ie: same amount of funds in the sector but spread across more companies. For simplicity, say if there are two companies in a sector with $1.5m invested in each totalling $3m in the sector, then a third company lists via an IPO then that would spread to $1m invested in each still totalling $3m for the sector. That has the impact of temporary pressure on the share price of the initial two companies in the sector.