Shares in RSA and Barclays were among the top risers in early trade, but overall the market was lower on a busy day for UK corporate earnings.
The FTSE 100 index was down 13.64 points at 7,288.61, with a number of firms falling after going ex-dividend.
Centrica also weighed on the market, dropping 3%. Annual profits at the group rose 4%, but its British Gas domestic business saw profits fall 11%.
RSA Insurance shares rose 4.7% after its full-year results beat forecasts.
The insurer reported operating profits of £655m, up 25% from the year before.
Shares in Barclays rose more than 2% after the bank reported a near trebling of full-year profits to £3.2bn.
BAE Systems rose 1.6% after the company reported annual operating profits of £1.74bn for 2016, up from £1.5bn.
"With an improved outlook for defence budgets in a number of our markets, we are well placed to continue to generate attractive returns for shareholders," said chief executive Ian King.
On the currency markets, the pound rose 0.2% against the US dollar to $1.2470 and edged 0.1% higher against the euro to 1.1806 euros.