From an opening price of $18.77, the shares fell by as much as 4.5% to under the $18 mark and then revived significantly, closing at $18.44.
That left the shares down 1.76% on the day but still at a higher mark than they were last Friday, when there was no hint that Ferguson was about to call it a day.
More fluctuations are likely until United settle on their replacement for the legendary Scotsman, who has been at the helm at Old Trafford for 26 years, long before the Glazer family became involved as owners.
The IPO prospectus hinted that volatility could be on the way last August, warning success could be dependent on when Ferguson left and who came in to replace him.
Their statement read: "We are highly dependent on members of our management, coaching staff and our players. Any successor to our current manager may not be as successful as our current manager."