Ultragenyx hits record low after bone disease drug fails late-stage trials

Shares of Ultragenyx Pharmaceutical RARE.O plunge 44.9% to a record low of $19.07

Stock set for worst day ever if losses hold

RARE says its experimental drug for a type of genetic bone disease did not meet the main goal in late-stage studies

The drug, setrusumab, was being developed for people with osteogenesis imperfecta, a rare genetic disorder that causes brittle bones

While the studies did not achieve statistical significance on fracture reduction, both showed meaningful improvements in bone mineral density, a key indicator of bone strength - RARE

Including session moves, stock down 54.2% YTD