When the meeting is called by the head guy you do. For some in that room, that may not have been the first time they have had to be called to a late night meeting to address an issue.

I thought about this, imagine if Jeremy Irons' and Simon Baker's characters would have showed up in sweatpants and polo-shirts, everything else the same, that would have been pretty cool huh
For example the line where Simon Baker says he is convinced the only option is to sell i all and that Demi Moore and Kevin Spacey can have another 45 minutes if they wanna calculate this, he is calling the man!
Also him shaving in sweatpants at night

"if seagal was thinner this could have been a theatrical product."

The meeting was at around 3am. They may not be in sweatpants but they also are not in their suits anymore. But yes, when there is an urgent emergency situation, it's serious business, and everyone will fully dress back up again. When Peter called the other two guys back up to show them his work, that was informal and I believe their ties were off and shirts a little unbuttoned.

Do you think these ppl change to adidas sweaterpants as soon as they get home or what?

"if seagal was thinner this could have been a theatrical product."