Shares of Tandem Diabetes Care Inc. soared in Tuesday's extended session after the medical device company named a new chief executive and posted better-than-expected quarterly results. Tandem said it named John Sheridan as new chief executive officer to succeed Kim Blickenstaff, who will become the new executive chairman of the board, effective March 1. The company also reported it swung to fourth-quarter earnings of $3.7 million, or 2 cents a share, from a loss of $11.4 million, or $1.23 a share, a year ago. Revenue rose to $76.2 million versus $40.3 million on the back of a 133% increase in pump shipments to 16,168 units. Analysts surveyed by FactSet had forecast a loss of 20 cents a share on revenue of $56.4 million. For 2019, the company expects sales in a range of $225 million to $270 million. Tandem Diabetes shares rallied 16% after hours.