That's right: never. All of these events (the latter coming last week at Morgan Stanley; nice going J. Mack!) typically happen on a Thank the Lord Above It's Friday. And that's largely because (1) firms don't want the bad press (believing reporters and readers do nothing but sip mint juleps and scotch from Friday at 5 p.m. until Sunday at 7) and (2) firms are, in general, a cowardly lot (believing their employees do nothing but drink Bud and Merlot from sundown on Friday until sundown on Sunday so any bad news will be greatly softened by bad beer and cheap wine).
But here's a little note to employers: the press isn't (that) stupid; readers actually do read papers (web pages) on Sundays (if not Saturdays); and employees get drunk an equal amount on Tuesday nights as they do on Friday nights (think: drink specials) and, to boot, are smart enough to smell the fear of executive management from several stalls away. So, Mr. and Mrs. Firms, if you want to keep up morale, I'd recommend you buck the trend of the weak, and give the kids the bad news first thing Monday morning. They might not like you afterward, but they'll still respect you.
When's the last time a company fired anyone on a Tuesday? Announced a pay cut on a Wednesday? Or revealed that their executive chairman would be receiving a pay raise of $1.2 million on a Thursday?