Generally anytime a company has big news it has to disclose, it will wait until Friday night after the markets close so that the news can be fully digested over the weekend and no snap decisions get made. Around 90% of shares traded worldwide are done by algorithms. So if investors get slightly panicked by a disclosure it can have a knock on effect when they want out, the algorithms pick up on it and the problem exacerbates. It also allows for the company to do some decent pr over the weekend justifying any decisions/outcomes.
Traditionally this is reserved for bad news - profit warnings, unfavourable trading updates etc. but the same principle applies to good news; volatility is never a good thing.
And whilst we all think this is great news, shareholders might not (non-football fans, just interested in making money from their investment).
Apologies for this rather dry response when the correct post in the thread should be "feck yeah", but you asked....