UK property platform Rightmove has knocked back a third acquisition offer from Australia's REA Group (REA), with Rightmove's Board of Directors characterising the improved proposal as unattractive and materially undervaluing of the business.

REA had on Monday increased its bid by 9 per cent to £7.70 per Rightmove share, valuing Rightmove at £6.1 billion ($11.9 billion). It came after the business declined a rejigged offer of £7.50 per share offer over the weekend, having first dismissed REA's first bid, worth £7.05 per share, as 'wholly opportunistic'.

REA has expressed disappointment at the latest rejection, noting the lack of substantive engagement with Rightmove, apart from the rejection of REA’s three previously disclosed proposals. In a note posted to the ASX, REA said it believed that the further improved proposal represents a compelling proposition for Rightmove’s shareholders, offering immediate value certainty in cash and the opportunity to benefit from the future value creation of the combined business.

REA urged Rightmove shareholders to encourage the Board of Directors of Rightmove to engage in constructive discussions with REA to work towards a recommended transaction, ahead of the deadline under Rule 2.6(a) of the Code on 30 September 2024.

REA first confirmed its interest in Rightmove at the beginning of the month, citing the "transformational opportunity" to expand its business in the United Kingdom.

REA Group CEO, Owen Wilson, has previously stated his belief the combination of REA's expertise and technology with the attractive Rightmove business will create an enhanced experience for agents, buyers and sellers of property.

"We are genuinely disappointed at the lack of engagement by Rightmove’s Board and we strongly encourage the Rightmove Board to engage," he said of the UK property giant's second rejection earlier in the week.

"We live in a world of intensifying competition and this proposed transaction would bring together two highly complementary digital property businesses for investment and growth. We have today increased our proposal to an implied value of 770 pence – it provides a combination of immediate value certainty in cash and at the same time gives Rightmove shareholders an increasing opportunity in core digital property and adjacencies where we have much expertise."