* STOXX 600 flat at close
* Trading cautious amidst U.S.-China trade talks, Trump legal woes
* Continental profit warning knocks autos (Recasts, adds quotes and detail, updates prices at close)
By Julien Ponthus
LONDON, Aug 22 (Reuters) - European stock markets ended broadly flat on Wednesday in a session of choppy trading amidst trade talks between the U.S. and China and uncertainty over U.S. President Donald Trump's legal woes.
The pan-European STOXX 600 was flat in percentage terms at its close as investors waited to see whether the United States and China could make progress towards resolving their trade conflict.
Political developments in the United States have had limited effects, at least so far. U.S. President Donald Trump's former lawyer, Michael Cohen, pleaded guilty to campaign finance violations on Tuesday and former campaign manager, Paul Manafort, was found guilty on charges of tax and bank fraud.
"Stock markets are mixed as trade talks still dominate the headlines," David Madden, market analyst at CMC Markets UK, said in a note. While a rise in the oil price boosted oil stocks and miners also powered ahead, autos were notable underperformers.
The sector dropped more than 3 percent and was on track for its biggest daily fall since the Brexit vote in June 2016 after automotive supplier Continental AG dropped more than 14 percent on the back of a profit warning.
Continental cut its 2018 sales and margin guidance, citing lower revenues, higher costs for developing hybrid and electric car technologies, and unspecified warranty claims.
"While most profit warnings are by definition a surprise, this one is all the more concerning as most of these headwinds were flagged and should have been evident when the company reported H2 results on 2 August; higher warranty costs being an exception," analysts at Jefferies said in a note.
Elsewhere, shares in Belgian biopharma Argenx rose 4.7 percent after Abbvie exercised an option to develop and commercialize a drug.
Among smaller companies, Adyen, the Dutch company which processes payments for Netflix and Facebook, reported H1 profit up 75 percent and jumped 4.3 percent.
Though Atlantia rose earlier in the session, shares in the Italian infrastructure group declined steadily throughout the day and ended nearly 4 percent lower.
The group said it had started looking at the impact on its shares and bonds of government plans to strip it of its motorway concessions after the Genoa bridge collapse.
Linde dipped 0.6 percent after warning that divestments needed to secure approval for its planned tie-up with Praxair had a size that would allow either party to abandon the deal.
The industrial gases supplier nevertheless added that it was in constructive talks to salvage the $83 billion merger. (Reporting by Julien Ponthus and Kit Rees Editing by Raissa Kasolowsky)