The significant insider selling of Ultragenyx Pharmaceutical shares, without any recorded purchases in the past year, might worry investors. Despite high insider ownership, the absence of insider purchases doesn't inspire confidence in the company's future.

The recent insider selling of Ultragenyx Pharmaceutical shares, despite the high level of insider ownership, raises caution. The lack of insider buying in the last twelve months also adds to this concern.

Ultragenyx Pharmaceutical's good top-line growth rate may not be the sole reason for its significant share price drop over the past three years due to larger than expected losses. Last year's underperformance suggests that the company still has challenges to resolve, perhaps attracting contrarian investors for a possible turnaround.