Several small- and mid-cap US stocks witnessed extraordinary volatility in the latest trading session, with a sharp divergence between top gainers and steep decliners, according to data timestamped Dec 16, 2025, 4:15 PM ET.
🚀 Top Gainers (Most Advanced)
Vision Marine Technologies (VMAR) surged 156.77%, leading the market amid heavy speculative interest.
AMC Robotics Corporation (AMCI) jumped 101.51%, marking a rare single-session double.
B. Riley Financial-related stocks dominated the leaderboard, with
RILYL up 91.36%,
RILYP rising 70.21%, and
RILY gaining 53.76%.
The sharp rally in B. Riley-linked securities suggests event-driven buying, possibly linked to restructuring activity, short covering, or corporate announcements.
📉 Top Losers (Most Declined)
Zynex Inc. (ZYXI) plunged 48.60%, the steepest fall of the session.
SaverOne 2014 Ltd. (SVRE) dropped 46.89%.
Radiopharm Theranostics (RADX) slid 43.65%.
Origin Materials warrants (ORGNW) fell 41%, while
Cingulate Inc. warrants (CINGW) declined 39.04%.
The sell-off in these names reflects risk-off positioning, profit booking, or adverse company-specific developments.
📌 Market Takeaway
The session underscored heightened volatility in speculative and low-float stocks, with gains and losses exceeding 40–150% in a single day. Such extreme moves highlight elevated trading risk and reinforce the importance of caution for retail and momentum-driven participants.
