Shares of J.C. Penney (JCP -3.7%) have given back around half of yesterday's gains as it looks like Bill Ackman's letter to the board may have created a situation that is more contentious than he bargained for.
"It's turned into a full-fledged boardroom brawl," CNBC's Scott Wapner says, referencing JCP's rather contemptuous response to the letter.
Yale's Jeff Sonnenfeld calls the Pershing Square chief "an angry guy going through his temper tantrums," before suggesting that it was indeed Ackman's actions (i.e. bringing in Ron Johnson) that tanked the stock in the first place.
The only thing to say here is that investors dislike uncertainty and the situation seems to have gotten a bit more uncertain for JCP after yesterday.