Shares of Green Dot plunged Monday after American Express and Walmart announced plans to launch a competing prepaid card service called Bluebird. Green Dot (GDOT) shares tumbled $2.60, or 20%, to end at $10.25. American
Valueworks Llc sold 13,521 shares as American Express Co. (AXP)’s stock declined 3.65%. The Valueworks Llc …