[NB: We made a simple math error below the first time; the correct number of what this might cost Barnes & Noble is $55.5 million, not $30.5 million.] The stock market has sent mixed signals at best regarding key retailers following Wednesday’s announcement of the Justice Department’s lawsuit (and settlement). On Wednesday itself, Barnes & Noble’s stock dropped sharply until someone stepped in and bought a million shares, rallying to recover much of the drop. The stock declined further on Thursday, and Friday morning it is down modestly again, having shed about $90 million in market cap since earlier this […]