Ann: Trading Halt, page-49

Generally speaking, it's the worst news that gets released on Fridays after close, and the best news tends to be released in the mornings. I see where you're going with it, but what tends to happen is that after close on Friday people stop watching and start thinking about their weekend, and whatever developments which occur over the weekend including Friday's sessions in most of the rest of the world get looked over on Sunday night and Monday morning, and whatever happened around 5PM on Friday eastern Australia time has been forgotten and obscured. On Monday morning you're much more likely to be focussing on the announcements just released that morning than what was happening last week.

Watch announcements which come out on Friday after 4.10PM and you'll pretty consistently see that they're bad ones. Look at the timings of quarterly reports etc and you'll see the good ones are released in the mornings and the worst ones as above.