Hobart's landmark Museum of Old and New Art (Mona) has racked up a staggering $408 million in losses since it opened in 2011, but founder David Walsh insists he is "completely happy with the finances".

Previously unreported corporate filings for parent company Moorilla Estate, which owns and operates Mona, show that at last count, the celebrated art museum, brewery, winery, spin-off festivals and other associated businesses lost $63 million in 2023-24, up from $60 million the year before.

More recent figures are not due for release until the first half of next year.

"Mona is financially where I want it to be," Mr Walsh told the ABC by email.

Mona founder David Walsh and his wife, artist Kirsha Kaechele. (Credit: Amy Brown)

"Mona will never make money [in and of itself], and it was never intended to. If I wanted to make money, I would have built it in Sydney, or Istanbul, or somewhere.

" I'm fine spending — I'm not the most committed capitalist — and I like building stuff. "

Mr Walsh is completing a $100 million extension at Mona, comprising a new wing of the gallery that will open in December and a library to open next year.

Before: The gallery in 2021. . . After: New construction in 2025. . . Instructions: Use left and right arrow keys to control image transition Before and after images SLIDE The gallery in 2021. / New construction in 2025.

He is also still contemplating a major hotel on the site, after a $400 million, 176-bed proposed development was shelved in 2021.

Mona ditches 'HoMo' name as it unveils plans for new hotel Mona's 2018 planned hotel development featured 172 rooms, a concert stage and a "nerd fest" library.

Signs on the construction site hoarding at Mona proclaim: "Yep, David's building something new. At this point, we've given up trying to stop him."

In round figures, Mr Walsh said Mona had cost him about $25 million per year long term.

He cited an unreleased 2018 report by Deloitte Access economics, which showed the gallery generated $135 million per year in direct and indirect economic activit