ITV's share price has gone from 173.8 in the final weeks of February to 142.9 as of last Wednesday, with an estimated £1.2 billion wiped off the value of the television group.
As previously reported, McPartlin was arrested on suspicion of drink-driving and subsequently reentered rehab and stepped aside from all future television commitments, meaning that Declan Donnelly will host the remaining two episodes of Saturday Night Takeaway alone.
The duo are big business for ITV, and have hosted some of ITV's most profitable ventures, including Britain's Got Talent and I'm A Celebrity - Get Me Out Of Here. They also earn an estimated £10 million per year in their deal with ITV in a deal that's expected to expire in the coming year.
Both I'm A Celebrity... and Britain's Got Talent are among ITV's most-watched programmes, and represent a significant portion of their potential to earn advertising revenue. While it's not yet clear when Ant McPartlin will return to TV screens, the pressure is now undoubtedly on for ITV to find someone to replace him or whether or not Declan Donnelly can go it alone as is.