Comparing CERN stock vs the S&P500, Dow Jones, and a related company ECLP and MDRX will show that all of them tanked the same week, and all of them recovered quite well within a month or so.
The link above is actually about the effect this memo had on the stock price. To quote:
A blunt e-mail message from Cerner Corp. CEO Neal Patterson about the work ethic of some employees caused the company's stock value to fall sharply last week. The company acknowledges the harsh tone of the message could have caused investors to question if the company was in crisis
...
After the e-mail was posted on a Yahoo! bulletin board last week, the stock fell nearly 20% on March 22-23, including 15%, or $6.13 per share, on March 23.
Patterson threatened installing time clocks, discontinuing an employee stock discount program and cutting staff by five percent, a morale blow at a company that prides itself on good employee relations. He told managers they had two weeks to get their units in shape, or "pack your bags." In a March 23 interview with the Kansas City Star, Patterson said threatening measures are not being pursued, but he continued to voice concern about work ethics in some segments of the company. He also sent out another e-mail apologizing for the harsh tone of the first one.
http://www.healthdatamanagement.com/news/4296-1.html
Comparing CERN stock vs the S&P500, Dow Jones, and a related company ECLP and MDRX will show that all of them tanked the same week, and all of them recovered quite well within a month or so.