I assume that the existence of the secondary market is what makes the IPO market successful. If people thought that the company felt it was acceptable to ignore their interests as soon as they got their money in the IPO, how many people would invest in the IPO?
One only need see the ire directed at Facebook by much of the tech industry for pricing their IPO in a fashion that benefited the company, but not the shareholders. Many feel that FB’s actions have damaged all other companies seeking capital for years, as Silicon Valley IPO’s may now be viewed with suspicion.
(Of course, the conspiratorially minded have noted that if there’s no IPO market to speak of, various technology firms requiring real capital will have no choice but to sell to the current leaders like… Facebook)