(Updates prices, adds Infineon comment in last two paras)
By Blaise Robinson
PARIS, April 23 (Reuters) - European stocks were down around midday on Wednesday as fresh worries over the banking sector eclipsed buoyant commodity-related stocks and prompted the market to surrender early gains.
Data showing a plunge in U.S. mortgage applications last week also fuelled concerns over the housing slump.
At 1219 GMT, the FTSEurofirst 300 <
> index of top European shares was down 0.7 percent at 1,296.12 points.The index has lost 14 percent so far this year as signs of a U.S. economic slowdown and a string of huge asset writedowns by banks have rattled investors.
Banks, hit by market talk of more writedowns and still under pressure following a massive rights issue unveiled by Royal Bank of Scotland <RBS.L> on Tuesday, were the top losers, with RBS down 6.2 percent, Banco Santander <SAN.MC> down 2.9 percent and UBS <UBSN.VX> down 3.4 percent.
Adding to the gloom, U.S. bond insurer Ambac Financial Group Inc. <ABK.N> posted a first-quarter loss after losses of $1.73 billion on its exposure to credit derivatives, bringing its net loss per share to $11.69, compared with Reuters estimates for a per-share loss of $1.82 in the first quarter.
"It's having a ripple effect on the rest of the sector," said one London-based trader. "People are more immune to writedown news but certainly headlines like these don't help."
Pharmaceuticals stocks were among the biggest gainers, with AstraZeneca <AZN.L> up 2.3 percent and Novartis <NOVN.VX> up 1.4 percent. GlaxoSmithKline <GSK.L>, which posted a 5 percent drop in quarterly earnings, was up 0.2 percent.
"Investors are prudent. It's a wait-and-see game as corporate results are coming out. We already got about a third of U.S. results for the quarter, and see that the "good surprises" ratio is a bit lower than what we normally get, while the "negative surprises" ratio is higher, which is common when the economy slips into recession," said Vafa Ahmadi, fund manager at CPR Asset Management, in Paris.
"The lack of visibility on the growth outlook and concerns over the credit crisis are holding investors at the moment. But since the Bear Stearns bailout, the mood has improved as people saw the Fed sending a signal that there will be no systemic crisis. The fear of a domino effect has diminished greatly." Belgian drugmaker UCB <UCB.BR> soared 21 percent after receiving a key regulatory approval for its Cimzia drug about a year earlier than expected.
Energy stocks rose on strong oil prices. U.S. crude oil futures <CLc1> eased under $118 on Wednesday, but were still within sight of an all-time peak of $119.90 reached on Tuesday.
Total <TOTF.PA> gained 1.1 percent and Royal Dutch Shell <RDSa.L> added 1.4 percent.
Germany's DAX index <
> was down 0.6 percent, the UK's FTSE 100 index < > down 0.7 percent and France's CAC 40 < > down 0.1 percent.Shares in Infineon <IFXG.n.DE> rose 3.9 percent after the Financial Times Deutschland reported the company was in talks with rivals Micron <MU.N>, Hynix <000660.KS> and Elpida <6665.T> to sell its 77 percent stake in Qimonda, while traders said Infineon itself could be the target of a private equity takeover attempt.
Infineon, which has said it is "evaluating its different alternatives", declined to comment. However, Chief Executive Wolfgang Ziebart told analysts on a conference call he had had no recent discussions with private equity.
(Additional reporting by Amanda Cooper in London; editing by Elaine Hardcastle)