** Battery-tech startup QuantumScape's QS.N shares fall 8.5% to $3.7 after UBS downgrades to "sell" from "neutral", trims PT to $2.5 from $5
** UBS raises concerns about QS' rollout of solid-state battery cell QSE-5, citing uncertainty around successful implementation
** Brokerage says co's exposure to luxury car brands such as Volkswagen-owned VOWG.DE Audi and Porsche P911_p.DE may be impacted by U.S. tariffs and could potentially limit units for the brands
** Key risks include economic downturn impacting luxury buyers, higher costs, slower EV adoption and uncertain profit margins, according to UBS
** One of 9 brokerages rate stock "buy", 6 rate "hold", 2 rate "sell"; their median PT is $5.65 - LSEG data
** Including session's moves, QS stock down 28.3% YTD
(Reporting by Padmanabhan Ananthan)
((Padmanabhan.Ananthan@thomsonreuters.com))