At the end of Wednesday's trading, the FTSE 100 was down 0.62% or 46.33 points at 7,478.62.
Banking stocks were among the top risers, with Lloyds Banking Group up 1.65% and RBS adding 1.35%.
Analysts said that struggling Spanish bank Banco Popular's rescue by Santander had given the overall banking sector a boost.
On the downside, pharmaceutical companies tumbled. Shire was the biggest faller on the 100-share index, dropping 3.2%.
Meanwhile, AstraZeneca lost 1% after its announcement that it had sold the rights for its migraine drug Zomig for $302m.
Colin McLean, manager of the UK growth fund at SVM Asset Management, said uncertainty over the outcome of the election so far appeared to be having little impact on investors.
"The bigger picture is that international stocks have been doing less well," he said.
"Quite a lot of what drove markets last year has gone into reverse over the last six months and investors are looking again at some of the beneficiaries of lower growth and deflation.
"That probably drives investors a little bit more than the election," he said.
On the currency markets, the pound rose slightly against the dollar, adding 0.33% to $1.2953. It rose 0.61% against the euro to 1.1517 euros.

Led by Rev Syd Graham, the private service for the couple from Bankfoot was held in Perth Crematorium on Crieff Road at 12:00.
The event lasted about 45 minutes and was also be broadcast on speakers outside the crematorium.
The funeral of Jim and Anne McQuire, the other Scots couple killed in the Sousse attacks, took place on Friday.
The Grahams were visiting the resort to celebrate Mrs Graham's 50th birthday.
Mr Graham, 51, had worked as a turnstile operator at St Johnstone Football Club for seven years.
They were among the 30 Britons who died in the attack on 26 June, which killed 38 people. Three Irish nationals, two Germans, one Belgian, one Portuguese and one Russian also died.

Castlepoint in Bournemouth opened in 2003 but the two-level car park has been reinforced with props since 2005 when it was found to be unsafe.
Bournemouth Borough Council has granted planning permission for it to be demolished and rebuilt in sections.
Work is expected to be completed by Christmas 2018.
Sean Jeffery, managing director of Kier Infrastructure UK, which built the shopping centre, said: "This is very welcome news. Together with the Castlepoint Partnership, we have worked hard to reach this stage.
"There remain a few key steps to put in place, but this consent brings us closer to being able to start work on-site."
The rebuild has been delayed for years as a result of legal wrangling.
Standard Life Investments, which manages the centre on behalf of Castlepoint Partnership, would not reveal the cost of the rebuild but said there would be no cost to tenants.
To minimise disruption, work will be carried out in five phases, each taking nine to 10 months, stopping for six weeks each Christmas.
Additional parking will be created underneath existing stores to maintain at least 2,500 spaces - the amount needed at peak times.
When the project is complete, the additional spaces will be turned into more shops.
The walkways in front of the upper level stores will also be replaced in phases.
The FTSE 100 closed slightly lower on the last day of campaigning before the general election.
[NEXT_CONCEPT]
The funeral for Billy and Lisa Graham, who were killed in last month's terror attacks in Tunisia, has taken place.
[NEXT_CONCEPT]
Work to rebuild a shopping centre car park that has been beset with structural problems for a decade will now go ahead in the spring of 2015.