Brisbane-based Suncorp is keen to finalise its merger bid for Promina after it had to release the details early following a leak to the market last week.

Industry analysts say the $7.7 billion bid – which Promina says it is favourably disposed to – was appealing to the board and bypassed an opening bid so that any potential rivals would have to contend with strong competition.

Promina CEO Mike Wilkins says the multi-brand group’s board “felt that this proposal was at a level we could not ignore, and we needed to put it in front of our shareholders”.

Suncorp is the fourth-largest general insurer and Promina the second largest, but there is speculation that market leader QBE will come in at the last minute with a better bid.

According to KPMG, the five biggest insurers in Australia hold 80% of the market, compared with 36% a decade ago.

Speculation is also rife that banker Westpac will launch a counter-bid for Suncorp. The Australian Financial Review says the banking group approached Suncorp about a deal several months ago but was rebuffed.