Dec. 8 (Bloomberg) -- European stocks had their first back- to-back decline in three weeks, led by insurers, this quarter's best-performing shares.

Axa SA, the region's second-largest insurance company, and Munich Re, the biggest reinsurer, paced the drop. JPMorgan Chase & Co. cut its recommendations on both, saying share prices more than reflect the outlook for earnings growth.

The Dow Jones Stoxx 600 Index lost 0.4 percent to 305.65 at 11:40 a.m. in London, with 15 of 18 industry groups falling. The Stoxx 50 also declined 0.4 percent, while the Euro Stoxx 50, a gauge for the 12 countries using the euro, fell 0.6 percent.

The Stoxx 600 reached a four-year high two days ago and has added 2.8 percent in the fourth quarter, as about two-thirds of its companies reported results that beat estimates.

A gauge of insurers is the top performer among the 18 groups this quarter, rising 12 percent. The measure dropped 1.2 percent today, posting the biggest decline. A measure of mining stocks, the year's top-performing industry on the Stoxx 600, also dropped today.

Insurance shares' gains this quarter are ``merited'' after corporate restructuring and ``opportunities in reinsurance'' that followed this year's U.S. hurricanes, JPMorgan analysts including Roger Doig said in a note today. ``We believe this is now largely factored into stock prices,'' he added.

National indexes fell in 14 of the 17 western European markets that were open. Germany's DAX Index dropped 0.6 percent, while France's CAC 40 Index fell 0.5 percent. The U.K.'s FTSE 100 Index was 0.3 percent lower.

Standard Chartered Plc, a London-based bank that makes about two-thirds of its profit in Asia, slid 3 percent to 1,179 pence. The lender fell 3 percent yesterday even after saying it expects full-year profit to increase ``broadly in line'' with analysts' estimates.

The Stoxx 600 Basic Resources Index, which includes BHP Billiton and Anglo American Plc, the world's two largest mining companies, fell 0.8 percent, the second-worst performance after insurance stocks. The measure has surged 45 percent this year, the most of any industry group.

KarstadtQuelle AG, Germany's biggest department-store chain, jumped 9.6 percent to 11.45 euros. It announced a plan to cut debt by 1 billion euros ($1.2 billion) this year by selling property and transferring a mortgage bank off the balance sheet.

PartyGaming Plc, the world's largest Internet poker operator, soared 9.6 percent to 128.25 pence, the biggest gain in the Stoxx 600. The company expects full-year earnings to beat analyst estimates, as sales growth accelerated at its PartyPoker site and more players used the company's online casino.

Shares in Tate & Lyle Plc, the world's only commercial maker of sucralose, fell after Morgan Stanley rated them ``underweight'' and said investors are underestimating the risk from generic rivals to the sugar substitute. The stock dropped 1.4 percent to 571.5 pence.

Nokia Oyj, the world's biggest maker of mobile phones, rose 1.9 percent to 15.44 euros, the highest since April 2004, after UBS AG and Merrill Lynch & Co. raised their share-price targets for the Finnish company.

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