MBX Biosciences announces equity offering after stock doubles

** Shares of MBX Biosciences MBX.O down 3.8% in extended trading to $19.25 as it looks to capitalize on its surging stock by raising equity

** MBX shares on Mon closed up 100% at $20 after co said its experimental drug, canvuparatide, met main goal in mid-stage trial for adults with chronic hypoparathyroidism, a hormone disorder that causes low calcium levels

** After the bell, the Carmel, Indiana-based firm announces 10 million share offering

** JP Morgan, Jefferies, TD Cowen and Guggenheim are joint bookrunners

** Co went public last Sept after IPO of 10.2 mln shares priced at $16

** With ~33.6 mln shares outstanding, co has about $672 mln market cap

** All 7 analysts covering MBX are bullish with avg rating of 'strong buy"; median PT is $45, per LSEG data