Ultragenyx Pharmaceutical (RARE) shares dropped 26% after a phase 3 study update of UX143 missed a key efficacy metric in pediatric and young adult patients with osteogenesis imperfecta, a rare genetic bone disorder.

"Investors were disappointed" that the annualized fracture rate efficacy hurdle wasn't met, Wedbush Securities said Thursday in a report. UX143 is being developed in collaboration with Mereo BioPharma (MREO).

More than 10 million shares of Ultragenyx traded intraday compared with a daily average of about 1.07 million. Mereo sank 41% following an increase in intraday trading volume to over 25 million from a daily average of about 1.41 million.

Methode Electronics (MEI) late Wednesday reported a wider adjusted net loss and declining net sales in fiscal Q4.

Shares slumped 25% as intraday trading volume surged to more than 1.2 million from a daily average of roughly 291,000.

Helen of Troy (HELE) shares sank Thursday after the consumer products firm issued a downbeat Q2 outlook amid uncertainty around tariffs, which dented Q1 revenue by more than expected.

Shares slid 22%, with intraday trading volume at over 3.72 million, versus the stock's daily average of about 741,000.

Price: 30.50, Change: -10.94, Percent Change: -26.40