When Is the Best Time of Day for a Company to Dump Bad News?

"Market watchers have long griped about companies that try to bury their bad news by releasing it late on a Friday afternoon. Earnings shortfalls, product recalls, outlandish severance deals—these things always seem to hit the wires just as we’re kicking off our pumps and wingtips for the weekend. The website Footnoted even runs a regular feature called the Friday Night Dump, in which it combs through end-of-the-week SEC FILINGS for dirty laundry.
But does this old PR trick even work in a world of 24/7 news services and social media? Not when it comes to earnings announcements, according to a working paper by Stanford Graduate School of Business accounting professor Ed deHaan and colleagues. In fact, by one measure, Friday filings might even get a little extra scrutiny—presumably the opposite of what those companies were hoping for."