Having been involved in a number of large deals in European football, the Italy-born Swiss banker convinced Markus Liebherr to purchase the troubled club in July 2009.
Liebherr passed away the following year but Cortese stayed on, overseeing Saints' rise from the foot of League One to the Premier League.
The club now lie fourth in the top-flight with the second-best defensive record in Europe, although the manner of their success has been controversial.
Alan Pardew was sacked two days after a 4-0 win at Bristol Rovers in 2010, with successor Nigel Adkins ruthlessly replaced earlier this year despite leading the club to back-to-back promotions and a decent start to life in the top flight.
Cortese defends the decisions, which were borne out of the desire to keep the club progressing.
"I remember when we changed with Alan Pardew it took about three weeks before we got a manager in," Cortese said at the Leaders in Football conference.
"On the first day everybody said, 'It is a stupid decision to make that change if you've not got anyone lined up'.
"Two years later you do the change and have someone lined up and it was controversial and a cruel decision.
"We changed managers on the back of good results and people say 'Why do you change now?', especially in Nigel's case as we came from 2-0 down to draw 2-2 [against Chelsea] at Stamford Bridge.
- Sports & Recreation
- Nigel Adkins
- Alan Pardew