From late December, Tower shares shed 24.7%, from $2.06 to $1.55. Its sharpest decline came immediately after the June 13 Christchurch quake; 14.8% was shed in the days following.
Its shares revived in late May when Tower announced a strong financial result, before the latest quake-induced plummet. Yesterday it retraced some losses, being up almost 2.6% to about $1.59.
Craigs Investment partners broker Chris Timms said there was uncertainty concerning several aspects of the insurance sector: the ability to get further insurance, the effect on the price of premiums and the public's reaction to any increases.
Tower shares had begun to unwind since the quakes, Mr Timms said.
The quakes had been "bad for business".
On May 27, taking into account Christchurch's September and February quakes, Tower posted a loss of $7.5 million, which was attributed to those earthquakes.
A loss of $5.7 million was booked against changes in the global investment market.
When announcing the result, Tower's group managing director, Rob Flannagan, said he was pleased Tower was in such a strong position after providing for more than $350 million of claims for the September and February earthquakes.
He said the full effect of the two Christchurch earthquakes could be up to $20 million after tax, because of the extra costs of reinsurance.
Mr Timms said yesterday Tower's predicament was reflected in Australian insurer QBE's shares, which had hit a record of $A19.60 ($NZ25.52) in late April, but then plunged 18% to a record low of $A16.07 by mid-June. However, QBE had also begun to retrace some losses to trade up at $A16.88 yesterday.
Mr Timms said if insurance premiums went up, people might pare back cover or go without.
