Market prediction and the Challenger disaster

Michael Trick has a post on Models, Information, and Market Rationality which shows a graph of the stock prices of Morton Thiokol, Lockheed, Martin Marietta, and Rockwell, in the hours after the Challenger disaster.
"The stock price for all of the companies immediately dropped 7-8% after the disaster. Within an hour, three companies went back up to being just 2-3% down, while one company further decreased: Morton Thiokol. The company responsible for the O-ring (of Richard Feynman and ice water fame): Morton Thiokol. It is certainly provocative that the market seemed to know something immediately that took an investigation months to determine. ...
But, as Bryan reminds me, this was not exactly a mystery to everyone at the time: the engineers involved strongly suspected early what the issue was and later fed that information to Feynman. So the information was out there and perhaps that information leaked out to the market in the immediate aftermath of the explosion. So perhaps it is not so mysterious after all. And there may well be other explanations for the larger drop off by Motton Thiokol."