you should be able to rest easy on the stock market, computers don't reset the clock at the second. at most it's once an hour. and i'll bet once a day if not start up.
not that that means some fool hasn't, tweaked the system for "better" time keeping.
i'd worry more about groups with a lot of cash(talking billions here) deciding to try to trash the exchanges.
remember the frozen OJ gag in trading places? opps. i mean don't worry, nothing bad can ever happen in the US. Katie said so.
and speaking of shady chi-com sites, anybody order a good balloon popping laser lately?