Shares of ev3, Inc. (EVVV) rallied more than 17% on Tuesday, the biggest advance in Russell 2000 Index, after medical device maker Covidien plc (COV) said it has agreed to acquire Plymouth, Minneapolis-based ev3. Inc., for $2.6 billion in cash in order to expand its business. Under the agreement, Covidien plans to pay $22.50 for [...]