BUZZ-Bayer shares soar over 18% after U.S. Supreme Court curbs Roundup lawsuits

** Bayer BAYGn.DE shares surged over 18% after the U.S. Supreme Court ruled in favor of the company's efforts to curb state-level lawsuits alleging its Roundup weedkiller causes cancer

** BAYGn has been accused of failing to warn of alleged cancer risks linked to its Roundup weedkiller

** Stock tops STOXX 600 index .STOXX

** BAYGn on track for best day since March 2003

** Ruling in Bayer's favour represents significant step towards glyphosate litigation containment, JPM says, expecting shares to outperform by 15-20% on Thursday