can anyone explain how accenture just went to a value of a penny even if it was momentary?
Regardless of the details, this is an example of how markets aren't perfectly efficient.
No. Just that the last reported transaction may not be `true' price.
There are other arguments against efficiency of markets, but this isn't.
[citation needed]
You might as well consult a historian.
According to the data I'm seeing for ACN now, the whole drop happened over a 1 minute period, and was back up the next minute.