Typically, yes.

It conveys an informality and casualness inappropriate to situation of declaring that you are about to disrupt a few thousand people's life in a massive way. Even posting it to Twitter before everyone has been notified is... a choice.

Some people won't perceive that, but plenty will, and appropriately so.

I severely doubt if the hiring teams at this company would take someone seriously if their application was sent in in this style. I severely doubt that they communicate with their clients and investors this way.

This is a financial services company, it goes with the territory that they should project careful attention to detail.

Even if this was a company in a much less serious industry, this is just not the kind of announcement that a CEO should send out without fixing all the squigly lines that helpfully tell you when you are about to come across as uneducated or unserious.