Ivan Levingston and Adeola Eribake, Bloomberg News The trading floor in the Frankfurt Stock Exchange, operated by Deutsche Boerse AG, in Frankfurt, Germany, on Monday, Dec. 14, 2020. The topsy turvy trade talks between the U.K. and the European Union took another somersault on Sunday when Boris Johnson and Ursula von der Leyen gave negotiators another shot at closing a deal. Photographer: Alex Kraus/Bloomberg , Bloomberg (Bloomberg) -- European startups are raising more money than ever before, producing a class of tech companies with valuations comparable to peers in the U.S. and Asia. But after a record-breaking start to the year, even some of the industryâs biggest cheerleaders are starting to worry that the momentum isnât sustainable.