Key Highlights

  • Acumen Pharmaceuticals leads the losers, trading down 85.77% to $0.33 after a failed Phase 2 Alzheimer's trial.
  • Solowin Holdings is down 44.73% to $2.05 following its 1-for-200 reverse split.
  • Alphatec Holdings is down 34.04% to $7.50 after third-quarter Revenue missed company expectations.
  • Arbor Realty Trust is down 28.97% to $2.15 after its board suspended the common dividend.
  • The five declines average 47.22%, a calculated figure, with a 56.80 point spread.

Which Stocks Are the Biggest Losers Today on October 30, 2026?

Five stocks lead the declines today, ranked here by the size of their percentage drop from largest to smallest. Each percentage is measured against that stock's own prior close, which in several cases is implied by the move rather than separately sourced, so the bases differ.

Acumen Pharmaceuticals (NASDAQ:ABOS) is trading down 85.77% at $0.33, followed by Solowin Holdings (NASDAQ:AXG), down 44.73% at $2.05, and ProMIS Neurosciences (NASDAQ:PMN), down 42.60% at $6.36. Alphatec Holdings (NASDAQ:ATEC) is down 34.04% at $7.50, and Arbor Realty Trust (NYSE:ABR) is down 28.97% at $2.15.

Three of the five have clear company news: a failed trial, a quarterly revenue miss and a Dividend suspension. For Solowin and ProMIS, no separate company announcement was identified, so no cause is assigned to either decline.

1. Acumen Pharmaceuticals: why did the stock collapse 86%?

Acumen shares are trading down 85.77% at $0.33 after topline results from its Phase 2 ALTITUDE-AD trial of sabirnetug in early Alzheimer's disease. The 542-participant study missed its primary iADRS endpoint at 18 months at both the 35 mg/kg and 50 mg/kg doses, and key secondary endpoints also failed.

The company said it will stop developing sabirnetug and evaluate strategic options, including its Enhanced Brain Delivery program. Amyloid plaque reductions were seen, yet about 10% of treated participants had ARIA-E edema.

Cash and marketable securities were $110.2 million at June 30, 2026, and about 72.3 million shares at $0.33 work out to a Market Value near $24 million, a calculated figure based on the June 30 share count.

2. Solowin Holdings: why is the stock sliding after its reverse split?

Solowin shares are trading down 44.73% at $2.05, and no company announcement beyond the split was identified for the decline. A 1-for-200 reverse stock split, announced on October 27, is meant to lift the price above Nasdaq's $1.00 minimum bid. The implied prior close is about $3.71.

Class A shares are set to fall from about 201.5 million to roughly 1.0 million, a count taken from one third-party summary. The company warned that it cannot guarantee the post-split price will hold.

The Hong Kong-based company combines brokerage with digital Assets and stablecoins. Fiscal 2026 revenue rose about 895% to roughly $28 million, but it posted a net loss of about $13 million. Data provider 52-week figures mix pre-split and post-split prices and are not comparable.

3. ProMIS Neurosciences: is the drop tied to Acumen's trial failure?

ProMIS shares are trading down 42.60% at $6.36, and no ProMIS-specific announcement was identified. Acumen reported its failed Phase 2 result the same day, and ProMIS's lead antibody, PMN310, also targets toxic amyloid Beta oligomers. Any link between the two moves remains unconfirmed.

The clinical-stage company held $53.4 million in cash and short-term investments at June 30, 2026, helped by $70.1 million of net proceeds from a January private placement, and management expects that cash to fund operations through 2027. The second-quarter net loss was $11.7 million.

With roughly 9 million shares, a data provider count, the price implies a market value near $57 million, a calculated figure. PRECISE-AD, a Phase 1b study of 144 patients, is due to report unblinded topline data in the first quarter of 2027.

4. Alphatec Holdings: why did shares fall 34% despite a higher EBITDA outlook?

Alphatec shares are trading down 34.04% at $7.50 after third-quarter results on October 29, 2026. Revenue rose 13% to $221 million, but the company said it fell short of expectations, mainly on lower Biologics attachment.

Full-year revenue is now expected near $862 million, against about $890 million in the February outlook. Free Cash Flow guidance fell to about $10 million from at least $20 million, though adjusted EBITDA guidance rose to about $137 million.

The spine-focused medical device company posted adjusted EBITDA of $38 million, a 17.3% margin, and a GAAP net loss of $5 million. The stock now sits near the low end of a 52-week range of $6.82 to $23.29, a data provider range that may have shifted since.

5. Arbor Realty Trust: what did the dividend suspension and Loan losses do to the stock?

Arbor shares are trading down 28.97% at $2.15 after third-quarter results on October 30, 2026, in which the board suspended the quarterly common dividend to preserve capital. Distributable Earnings were a loss of $0.04 per share, against a $0.35 profit a year earlier, and the GAAP net loss to common holders was $85.4 million, or $0.51 per share.

Non-performing loans rose to $647.6 million across 32 loans from $428.8 million across 19 loans at the end of June, and the company booked a $53.0 million net loan loss provision.

The Mortgage REIT, which lends against multifamily and single-family rental properties, had stockholders' Equity of $2.55 billion at quarter-end. Before the drop, a data provider showed a Price-to-Book Ratio near 0.26 and a one-year share decline of about 75%.

Losers Side by Side: Average Collapse, Spread and Price Gap

The five declines average 47.22% (calculated), and the spread between the largest and smallest drop is 56.80 percentage points (calculated). Acumen's fall is about 2.96 times the size of Arbor's (calculated). Bases differ, since the prior closes are implied from each move.

Prices span a wide range as well. ProMIS at $6.36 trades roughly 19 times Acumen's $0.33 (calculated), and three of the five trade at or below $2.15.

The causes fall into three groups. Acumen and Alphatec reacted to company disclosures about a trial and a revenue miss, Arbor to a dividend suspension, and Solowin and ProMIS to events with no stated company trigger. Only Alphatec paired a cut to its revenue outlook with a raised adjusted EBITDA target.

What to Watch Next: Biomarker Data, the PRECISE-AD Readout and Dividend Status

Arbor's dividend suspension took effect on October 30, 2026, so attention turns to whether non-performing balances stabilize in the fourth quarter. ProMIS expects all PRECISE-AD patients to finish 12 months of dosing by the fourth quarter of 2026, with unblinded topline data due in the first quarter of 2027.

Acumen has promised more biomarker and imaging data in the coming weeks, without a specific date. No dated release was identified for Alphatec or Solowin, though Alphatec investors will watch biologics attachment in the fourth quarter and Solowin must hold the stock above $1.00 after its split.