MongoDB shares rise after $1 billion buyback
** Database software firm MongoDB's MDB.O shares rise 5.8% to $356.8
** Co authorizes an additional $1 billion share buyback, bringing total authorization to $2 billion — SEC filing
** Out of the $2 billion, $1.35 billion remains available for future share repurchases
** On Monday, shares tumbled 18.3% after the co announced a CEO transition
** 35 of 43 brokerages rate the stock "buy" or higher and eight "hold"; median PT is $470
** Including the session's moves, MDB down 15.4% YTD