Shares of athenahealth, Inc. (ATHN, Financial) were up 16.4% in the quarter. The company reported better-than-expected growth in the number of physicians added to the company’s network as well as better-than-expected margins. We continue to have conviction in the investment thesis because we believe athena has a compelling software-enabled-service offering and will continue to gain market share.
From Baron Opportunity Fund's third quarter 2015 letter.