Harvey Norman co-founder and chairman Gerry Harvey has put his money where his mouth, buying up $12.7 million worth of shares this week after claiming the company was undervalued.

Across Monday, Tuesday, and Wednesday, Harvey bought 3.3 million shares, at roughly $3.84 a piece.

The day after Harvey Norman delivered lacklustre financials, Harvey argued the company’s shares, then sitting at $3.78, were in fact worth “six to eight bucks”.

Harvey believes the retail group’s property portfolio are badly underestimated — in the books at $3.9 billion and up $107 million during the half after external valuers reappraised the properties.

“There is no value attributed to that whatsoever,” he told the AFR last week.

“In fact, it works a bit the opposite way, where they start to question the value of our property.”

Shares in Harvey Norman are down 0.4 per cent today, sitting at $3.84 at 1:15pm AEDT.