[mahmud]

Never heard of this theory. Black refers to ink color. Line items in red are loses, black are break-even or profit. Black-friday is when retailer make so much profit they get back in black.

Business type-writters had red and black ribbons.

[jeffcoat]

Wikipedia presents both origin stories, but the accounting version (black ink) does appear to be a 1980s back-formation trying to put a nicer spin on the name.

http://en.wikipedia.org/wiki/Black_Friday_(shopping)#Origin_...