Key Highlights

  • LENZ Therapeutics has the longest days to cover at 18.9, with 37.74% of float sold short as of August 31, 2026.
  • Novavax has the largest short position at 46.05 million shares, or 27.92% of shares outstanding.
  • C4 Therapeutics is trading 7.83% higher at $3.46 with 34.7% of shares outstanding sold short.
  • Capricor has 37.62% of float sold short ahead of an FDA target action date of November 22, 2026.
  • Four of the five are trading higher on October 28, 2026, and only LENZ Therapeutics is lower, down 1.43%.

Which Biotech Stocks Are the Most Shorted on October 28, 2026?

Five biotech stocks with large short positions are on the move on Wednesday, October 28, 2026. LENZ Therapeutics (NASDAQ:LENZ) is trading 1.43% lower at $3.11 with 37.74% of float sold short, while C4 Therapeutics (NASDAQ:CCCC) is trading 7.83% higher at $3.46, Abeona Therapeutics (NASDAQ:ABEO) 2.66% higher at $4.57, Novavax (NASDAQ:NVAX) 2.12% higher at $10.23 and Capricor (NASDAQ:CAPR) 4.34% higher at $6.36 ahead of an FDA decision due by November 22, 2026.

The five are ranked by days to cover, which compares shares sold short with average daily volume, from longest to shortest. Share-of-float and share-of-shares-outstanding percentages are not directly comparable, and the settlement dates differ (August 31 for LENZ Therapeutics, September 30 for Novavax and October 15 for the rest), so the percentages are shown but not used for ranking.

1. LENZ Therapeutics: What Does 18.9 Days to Cover Mean for a Stock Trading 1.43% Lower?

LENZ Therapeutics is trading 1.43% lower at $3.11 after a $3.16 close on October 23, 2026, with no dated company release behind the move. Short-interest data for the settlement date of August 31, 2026 show 10,874,649 shares sold short, equal to 37.74% of float and 18.9 days to cover, the longest of the five. That reading is the oldest of the group.

The company sells VIZZ, an FDA-approved treatment for presbyopia, and reported second-quarter net product sales of $1.736 million and total revenue of $5.486 million against a net loss of $31.918 million. Cash, equivalents and marketable securities were $220.0 million at June 30, compared with a market capitalisation of $102.74 million at the October 16 close.

2. C4 Therapeutics: How Does 16.95 Days to Cover Sit With a 7.83% Rise?

C4 Therapeutics is trading 7.83% higher at $3.46, an implied prior close near $3.21 (calculated), with no announcement dated today. Short interest was 42,722,018 shares for the October 15, 2026 settlement, about 34.7% of shares outstanding because no separate float figure was published, with 16.95 days to cover on average daily volume of 2,520,136 shares.

The Watertown, Massachusetts company designs medicines that break down disease-causing proteins, with cemsidomide for multiple myeloma at the center of its plan. Phase 1 data showed a 53% overall response rate at the 100 microgram dose, from a small sample. Cash, equivalents and marketable securities were $300.4 million at June 30, 2026, and management expects them to fund operations through the end of 2028.

3. Abeona: Is 12.70 Days to Cover a Crowded Trade at $4.57?

Abeona is trading 2.66% higher at $4.57, an implied prior close of about $4.45 (calculated), and no dated release accompanied the move. Short interest was 17,214,886 shares at the October 15, 2026 settlement, up 331,997 from the prior period, or about 30.1% of shares outstanding (calculated), with 12.70 days to cover.

The cell and gene therapy company's Zevaskyn, a treatment for recessive dystrophic epidermolysis bullosa, produced $11.4 million of second-quarter net product revenue, up 31% from $8.7 million. Cash, equivalents and short-term investments were $146.8 million at June 30, 2026, and the quarterly net loss was $20.2 million.

4. Novavax: How Can the Largest Short Position Take Only 8.08 Days to Cover?

Novavax is trading 2.12% higher at $10.23, an implied prior close near $10.02 (calculated), and no dated release accompanied the move. Short interest was 46.05 million shares, the largest count of the five, for the September 30, 2026 settlement, equal to 27.92% of shares outstanding and 8.08 days to cover. The prior report showed 49.88 million shares.

Second-quarter revenue fell 76% to $57 million and the net loss was $53.4 million, yet management raised its 2026 adjusted revenue guidance to $235 million to $275 million. Cash, marketable securities and restricted cash were $724 million at June 30, and a $125 million milestone from Sanofi (NASDAQ:SNY) is triggered when the Phase 3 COVID-influenza combination trial starts in the U.S. or EU.

5. Capricor: What Does 37.62% of Float Sold Short Mean Before the November 22 FDA Decision?

Capricor is trading 4.34% higher at $6.36, an implied prior close near $6.10 (calculated), with no dated announcement on October 28. Short interest was 19,860,451 shares for the October 15, 2026 settlement, or 37.62% of float, with about 6.6 days to cover, the shortest of the five. The position is up 5.5% from 18,825,352 shares on September 30.

The FDA extended its target action date for deramiocel, a cell therapy for Duchenne muscular dystrophy, to November 22, 2026 from August 22. In July an FDA advisory committee voted 9 to 3 against the strength of the evidence on heart benefits. The second-quarter net loss was $40.7 million, or $0.70 per share.

Most Shorted Biotech Stocks Compared: How Do Days to Cover, Share Counts and Moves Differ?

Days to cover range from 18.9 for LENZ Therapeutics to about 6.6 for Capricor, a gap of 12.3 days (calculated). In share terms the order changes: Novavax has 46.05 million shares sold short against 10.87 million at LENZ Therapeutics, a difference of 35.18 million shares (calculated). The moves also differ, with C4 Therapeutics up 7.83% and LENZ Therapeutics down 1.43%, a spread of 9.26 percentage points (calculated).

LENZ Therapeutics and Capricor are close on share of float, at 37.74% and 37.62%, only 0.12 percentage points apart (calculated), but those readings come from August 31 and October 15. C4 Therapeutics, Abeona and Novavax are measured against shares outstanding, so their percentages cannot be merged into one ranking. LENZ Therapeutics' $220.0 million of cash and securities at June 30 exceeds its $102.74 million market capitalisation at the October 16 close by $117.26 million (calculated).

What to Watch Next: The October 30 Settlement Date, Capricor's November 9 Report and the November 22 FDA Action Date

The next short-interest settlement date is October 30, 2026, with publication expected around November 10, which will update the C4 Therapeutics and Abeona positions. Capricor's quarterly report is estimated for November 9 and the FDA target action date for deramiocel is November 22, 2026. Abeona is expected to report third-quarter results in mid-November, while Novavax awaits third-quarter results and the outcome of regulatory talks on the timing of the combination trial. LENZ Therapeutics' third-quarter results and its next short-interest release are also ahead.