KFC has closed around 750 out of its 900 strong UK outlets owing to supply issues that meant it ran out of chicken.
It comes shortly after KFC switched its supply contract to DHL from long-standing supplier Bidvest.
Shares in KFC owner Yum Brands were down by around 0.9% in New York trading on Monday.
“We've brought a new delivery partner onboard, but they've had a couple of teething problems - getting fresh chicken out to 900 restaurants across the country is pretty complex!,” said KFC on twitter.
While most of the UK restaurants were closed on Monday, many others were operating on shortened hours.
Yum and KFC UK issued an apology to customers.
“We know that this might have inconvenienced some of you over the last few days, and disappointed you when you wanted your fried chicken fix – we’re really sorry about that,” said Yum in a statement.
Yum shares had already sold off following fourth-quarter results, with the stock around 7% lower over the past month.
Overall system sales rose by just 1% in the quarter with 4% growth from KFC compared with losses of about 2% from both Taco Bell and Pizza Hut.
However, much of the system sales comprises of revenue that goes to franchisees.
With KFC currently stepping up its refranchising efforts analysts expect Yum´s 2018 revenue to decline by around 20%.