By Sara Sjolin, MarketWatch

LONDON (MarketWatch) -- European stock markets dropped from multiyear highs on Wednesday as Deutsche Lufthansa and Vallourec slumped more than 10% after profit warnings.

The Stoxx Europe 600 index gave up 0.6% to end at 347.74, after closing at the highest level since January 2008 on Tuesday.

Shares of Deutsche Lufthansa slid 14% after the airline cut its operating profit forecast for 2014 and said it no longer expects to achieve its 2015 operating result target. The loss marked the worst one-day percentage drop for Lufthansa since Sept. 11, 2001, when the stock sank 15%, according to FactSet data.

Meanwhile, Emirates canceled an order for 70 A350 long-range jets, further sending shivers through the airline sector. Airbus Group NV lost 3.1% after the announcement. Engine-maker Rolls-Royce Holdings PLC said its order book will fall about 3.5% because of the Emirates cancellation, and that sent its shares 5.5% lower.

International Consolidated Airlines Group SA (ICAGY) dropped 3.1%, Air France-KLM SA lost 7% and SAS AB gave up 3%.

Vallourec tumbled 11% on news the steel-pipe maker late Tuesday cut its full-year guidance for 2014 after large clients delayed orders until next year. Credit Suisse and Exane BNP Paribas both cut the company to neutral from outperform, while J.P. Morgan Cazenove downgraded the stock to underweight from neutral.

Aside from corporate news, investors digested the recent rally in equities that was spurred by the European Central Bank's aggressive stimulus measures announced last week. The Stoxx 600 was at a more than six-year high on Tuesday, Germany's DAX index was close to a record high and the S&P 500 (SPX) and Dow Jones Industrial Average (DJI) were hovering around all-time highs, and there is now concern that the "positive momentum is beginning to flag," Mike van Dulken, head of research at Accendo Markets, said in a note.

"That's not to say we necessarily expect a correction, but at least a sideways move as a pause for breath following recent gains," he said.

U.S. stocks also traded lower on Wednesday.

World Bank growth downgrade

The World Bank also gave investors food for thought, trimming its global growth forecast for 2014 to 2.8%, down from its 3.2% forecast in January. The institution said the harsh winter in the U.S. and the Ukraine conflict has bruised the outlook for economic growth globally this year.

In its report, the World Bank also warned of a "hard landing" in China that could weigh down East Asian countries and hurt commodity exporters.

Among country-specific indexes in Europe, Germany's DAX 30 index closed 0.8% lower at 9,949.81, while France's CAC 40 index lost 0.9% to 4,555.11.

U.K. labor-market data

The U.K.'s FTSE 100 index fell 0.5% to 6,838.87, as stronger-than-expected unemployment data added more pressure on the Bank of England to hike its key lending rate. The U.K. joblessness level for the three months to April fell to 6.6% from 6.8% in the three months to March, beating forecasts of a 6.7% reading.

Wage growth, however, slowed markedly in April, with average salaries including bonuses improving 0.7%, down from 1.9% in March. Earnings growth have become an increasingly important factor for the Bank of England after the central bank scrapped its initial forward guidance that focused mainly on the headline unemployment rate.

The slow salary increase in April was mostly due to the impact of a top-bracket income tax change that boosted pay this time last year, according to analysts.

Outside the major indexes, shares of Banca Monte dei Paschi di Siena SpA sank 20% as the bank carried on with capital increases aimed at raising EUR5 billon to avoid nationalization.

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