By Sara Sjolin, MarketWatch

LONDON (MarketWatch) -- Erasing earlier gains, European stock markets headed for a fourth straight day in the red on Wednesday, with investors waiting for minutes from the U.S. Federal Reserve's latest meeting to help set the trading tone.

The Stoxx Europe 600 index gave up 0.3% to 339.12, after posting the biggest loss in four months on Tuesday.

The recent losses have come after global stock markets last week traded at or near record highs, creating fears of an asset bubble and spurring concerns that a correction is due. Specifically for Europe, a string of disappointing German data has also highlighted weaknesses in the euro zone's powerhouse and led to concerns the country is heading toward zero economic growth. Read: Is Germany leading the euro zone toward the no-growth cliff?

A dearth of economic data for Europe on Wednesday meant that investors instead focused on key central-bank events. European Central Bank President Mario Draghi is due to speak in London in the evening, while Executive Board members Benoît Curé and Peter Praet spoke in Athens and Paris, respectively. Praet said the ECB's targeted long-term refinancing operation will break a vicious spiral of high lending rates for companies, high credit risk and poor economic performance.

The main event, however, will be the release of minutes from the Fed's June meeting due at 7 p.m. London time, or 2 p.m. Eastern Time. Fed Chairwoman Janet Yellen is clearly among the doves on the policy-setting committee, and investors are hoping that the minutes will "provide some clarity and reassurance that Yellen can continue to hold sway over her more hawkish colleagues," Rebecca O'Keeffe, head of investment at stockbroker Interactive Investor, said in a note. Read: Minutes may shed some light on how and when the Fed will hike

After a solid June jobs report out last week, several banks have moved forward their forecast as to when the Fed will introduce the first rate hike.

Europe movers

Back in Europe, the U.K.'s FTSE 100 index suffered one of the biggest setbacks among country-specific indexes, down 0.6% to 6,698.10. Admiral Group PLC , slid 5.4% in London after the insurer reported a drop in first-half turnover.

Other insurance companies fell alongside Admiral, with shares of Aviva PLC down 3.5% and Legal & General Group PLC 1.2% lower.

Also in London, shares of BP PLC (BP) lost 1.4% after Deutsche Bank cut the oil major to hold from buy, according to Dow Jones Newswires.

More broadly in Europe, airlines rebounded after a sharp selloff on Tuesday sparked by a profit warning from Air France-KLM . On Wednesday, Air France-KLM climbed 1.1%, Deutsche Lufthansa AG gained 0.6% and EasyJet PLC picked up 1.8%.

Gemalto NV added 2.6% in Amsterdam after Morgan Stanley lifted the digital-security company to equal-weight from underweight.

Germany's DAX 30 index slipped 0.1% to 9,764.48, and France's CAC 40 index fell 0.1% to 4,339.95.

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