** Shares of U.S. insurance provider Kemper Corp KMPR.N fall 3% to $39.92 premarket
** William Blair downgrades stock to "underperform" from "marketperform"
** Brokerage says co faces dual threat of overexposure to a worsening California market and big competitors coming down into the non-standard segment
** Says KMPR to face greater downside risk if it continues to face significant adverse development in its commercial auto business
** Three of 6 brokerages rate stock "buy" or higher, 2 "hold" and 1 "sell" or lower; median PT is $110 - data compiled by LSEG
** As of last close, stock down 38% YTD
(Reporting by Koyena Das in Bengaluru)
((Koyena.das@thomsonreuters.com))