IGNIS Asset Management, an institutional shareholder in both Aviva and RSA, said a deal between the two insurers remained possible although RSA would have to raise its bid proposal for some Aviva units.
Ignis owns roughly 0.5 per cent of Aviva's share capital and around 1.5 per cent of RSA's share capital.
RSA said it was open to talks with Aviva after it rejected RSA's £5bn bid proposal for some of Aviva's main general insurance businesses.
"I think the deal definitely remains possible," Ignis Asset Management investment manager Martin Brown said.
Brown said RSA's approach undervalued the Aviva businesses.
However, he added RSA would not necessarily have to raise its bid approach by much in order to oblige Aviva to put the proposal to its shareholders and for a deal to remain accretive for RSA's own shareholders.
"There's no reason for the deal to be dead other than for RSA to be unwilling to pay more, but RSA would not have to raise its offer by much for Aviva to be obliged to consider it.
"A ten per cent increase might be enough to persuade Aviva to consider it, or to oblige Aviva to put it to its shareholders."
City A.M. Reporter