In situations where there is a deal being stuck which can (and will) affect the stocks of either company, the company management has to enforce chinese walls around such deals to prevent insider information leaks. The management cannot possibly make all employess know about the deal and them make all of them come under an NDA or have all employees have access to such material non-public information. You do realize that this is strictly material non-public information and such data dissemination falls under strict regulatory rules (like SEC rules in USA). That is why Chinese walls are enforced before any big deal is supposed to go through and only people involved directly in such deal-making are kept in the loop. I think this is pretty standard corporate practice in all big companies these days.