"ZPG's proposal is highly opportunistic and fundamentally undervalues the company and its prospects", Sir Peter Wood, GoCompare's chairman, said of the approach, which was made on November 8.
GoCompare Group PLC on Tuesday confirmed that ZPG PLC made an unsolicited approach about combining the two businesses last week which valued the firm at roughly about GBP460.2 million.
ZPG also made an all-shares bid on May 26 that had been pitched at the same price and was spurned on the same grounds, the insurance-focused price comparison firm disclosed.
GoCompare, responding, said the proposal envisaged an offer at 110.0 pence per share, which GoCompare said "fundamentally undervalues" the business as it was trading at that price less than one month ago. "Since May, GoCompare has delivered H1-2017 results which were ahead of expectations".
ZPG operates some of the UK's most well-known digital platforms, including Zoopla, USwitch, PrimeLocation, Money, Hometrack, and The Property Software Group.
GoCompare shares jumped 10 percent to 102 pence on news of the approach, while shares in the Zoopla-owner edged up 0.4 percent to 338 pence, valuing it at about 1.5 billion pounds. It did not rule out accepting a higher offer.
GoCompare is working with advisers from Deutsche Bank.