The club, listed on the New York stock exchange, was up 1.3% to 17.2 US dollars (£11.75) at one stage, amid hopes the self-proclaimed "special one" could bring a new era of glory to the club.
The rally comes after the decorated Portuguese manager was appointed on a three-year deal on Friday.
The commercial power of the Manchester United brand has remained strong, despite a below-par performance on the football pitch compared to trophy-laden seasons of the past.
It announced at the beginning of the month that commercial revenues had surged 38% to £65.8 million in the third quarter, as it confirmed five new sponsorship deals.
It said retail, merchandising, apparel and product licensing revenue also rose by £16.8m to £24.4m, compared to the third quarter of last year.
However, failure to secure Champions League football last season is expected to put a hefty dent in its finances of around £30m.