As Adrian Room's revision of Brewer's Phrase and Fable reminds us, these are but a few examples of quotidian despair, but he, too, overlooks the paradox that days upon which people went bankrupt are not Red. The American slang, to be "in the black", is first noted by the OED in 1928, but, as does Room, it overlooks the fact that Black Friday was the joyful day after Thanksgiving when traders found that their accounts were sent into the black by Christmas shoppers.
"A WORD of difficult history." So the OED notes of black. As a synonym for doom-laden, will it remain linked with Norman Lamont's Black Wednesday (1992) or will popular memory revert shudderingly to the events of Black Monday (1987) or even those of Black Thursday and the Crash.