The Irishman told BBC Radio Cambridgeshire: "I'm not going to lie, my own business has struggled badly over the last three years.
"But I've been prudent with my own money and will continue to put money into the football club."
MacAnthony has amassed a fortune through overseas property development, but has seen his business interests suffer as a result of the recession.
Posh were relegated from the Championship earlier this month just a year after winning promotion from League One.
They made former Bristol City boss Gary Johnson their fourth manager of the season ahead of Saturday's match with Leicester.
"I've told Gary that I will invest whatever it takes to win League One and I've always backed my managers," he said.
"Even in the Championship this season I've spent £2m in transfer fees and £220,000 on loan signings in January."
Meanwhile, Cambridgeshire Police have confirmed that they are investigating threats made against MacAnthony and his family.
The 34-year-old has said he believes the threats relate to customers left in a difficult position following the economic climate.
"Everyone knows the recession has hurt a lot of people over the last few years, but people who bought properties and couldn't complete the deals because they couldn't get mortgages cannot blame me," he said.
"If banks stop lending money, what can you do? These articles are nothing new, it's repetition - the same stories over and over again.
"This is something I've lived with for many years and it's nothing new, but there are people out their with little minds and I won't be losing sleep over it."
Source: BBC Sport
Source: BBC Sport