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Geron GERN

US equityMarket cap rank #3434Biotechnology
$1.20 −$0.01 (-0.83%)
Pre-market · Oct 8, 8:20 am ET · After hours $1.20 0.00%
Open$1.21
Prev close$1.21
Day range$1.19 – $1.22
Volume5.14M
Market cap$770.97M
P/E (TTM)–
Dividend yield–

Ownership & positioning

Who holds it, who is betting against it, and where the big money is moving

Institutional ownership74.8%+0.01 pts vs. prior quarter
Institutions holding291+0 vs. prior quarter
Insider trades (recent)46 buys / 3 sellsNet buying
Short interest12.86% of floatDays to cover 6.7 · as of 15 Sep 2026
Short-sale volume share11.6%5-day average of daily volume

Short-sale volume as % of daily volume

6%11%15%19%Sep '26Sep '26Oct '26

Large-order net flow, last 20 sessions

Net of large-order buying minus selling, in USD. Over this window: −$7.74M (8 inflow days, 12 outflow days).

Net flow by order size, last 20 sessions

−$6.8MSuper−$947.6KBig−$3.1MMid−$11.2MSmall

Super/Big orders approximate institutional-size trades; Mid/Small approximate retail-size trades. Net buy minus sell value in each bucket, summed over the window.

The five largest holders on file together own 31.4% of shares outstanding.

Largest holders

  • BlackRock7.64%
  • RA Capital Management, L.P.6.66%
  • Soleus Capital Management, L.P.6.66%
  • State Street Global Advisors5.58%
  • Vanguard Capital Management, LLC4.86%
  • Citadel Advisors LLC4.52%
  • ClearBridge Investments, LLC3.06%
  • Eversept Partners, L.P.2.91%

By investor type

  • Mutual Fund35.68%
  • Hedge Fund22.30%
  • VC/PE Fund9.19%
  • Public Company6.12%
  • Private Company0.91%
  • Insurance Company0.30%
  • Government Pension Fund0.27%
  • Individual/Insider0.08%

Reported short interest has risen from 12.50% to 12.86% of float over the last 6 biweekly reports (30 Jun 2026 to 15 Sep 2026).

Recent institutional activity

HolderTypePeriodShare changeNew stake
Citadel Advisors LLC Hedge Fund 2026/Q3 +7,462,359 4.5%
Vanguard Portfolio Management, LLC Mutual Fund 2026/Q3 +6,143,815 1.7%
The Goldman Sachs Group, Inc. Public Company 2026/Q3 +5,370,752 2.5%
State Street Global Advisors Mutual Fund 2026/Q3 +5,359,488 5.6%
The Toronto-Dominion Bank Public Company 2026/Q3 +4,107,289 0.7%
Renaissance Technologies Corp. Hedge Fund 2026/Q3 +2,779,479 0.7%
PanAgora Asset Management, Inc. Mutual Fund 2026/Q3 +2,578,624 0.5%
ExodusPoint Capital Management, LP Hedge Fund 2026/Q3 +2,514,158 0.4%
Two Sigma Investments, LP Hedge Fund 2026/Q3 +2,418,545 0.7%
BNP Paribas Financial Markets SNC Private Company 2026/Q3 +1,989,743 0.4%
Qube Research & Technologies Ltd Mutual Fund 2026/Q3 +1,915,725 0.5%
BlackRock Mutual Fund 2026/Q3 +1,795,792 7.6%
Candriam, Société En Commandite Par Actions Mutual Fund 2026/Q3 +1,667,706 0.9%
Soleus Capital Management, L.P. Hedge Fund 2026/Q3 +1,300,000 6.7%
Moore Capital Management, LP Hedge Fund 2026/Q3 +1,191,941 0.2%

Institutional buy/sell activity by reporting period, largest moves first.

Insider transactions

DateInsiderTitleTransactionSharesPriceHeld after
29 Sep 2026 Robert Jay Spiegel Independent Director Other Acquisition +6,351 $1.23 212,161
29 Jun 2026 Robert Jay Spiegel Independent Director Other Acquisition +6,103 $1.28 205,810
19 May 2026 Elizabeth O'Farrell Lead Independent Director Other Derivative Acquisition +220,000 $1.26 220,000
19 May 2026 Robert Jay Spiegel Independent Director Other Derivative Acquisition +220,000 $1.26 220,000
19 May 2026 Susan Molineaux Independent Director Other Derivative Acquisition +220,000 $1.26 220,000
19 May 2026 John McDonald Independent Director Other Derivative Acquisition +220,000 $1.26 220,000
19 May 2026 Dawn Bir Independent Director Other Derivative Acquisition +220,000 $1.26 220,000
12 Apr 2026 Timothy Williams Executive Vice President Other Derivative Acquisition +2,500,000 $1.73 2,500,000
30 Mar 2026 Robert Jay Spiegel Independent Director Other Acquisition +5,243 $1.49 199,707
24 Mar 2026 Patricia Susan Andrews Director Other Derivative Acquisition +270,000 $1.57 270,000
24 Mar 2026 Constantine Chinoporos Director Other Derivative Acquisition +270,000 $1.57 270,000
17 Feb 2026 Michelle Robertson Executive VP, CFO, Treasurer and Principal Financial & Accounting Officer Derivative Exercise and Sale -9,855 $1.94 17,645
17 Feb 2026 Michelle Robertson Executive VP, CFO, Treasurer and Principal Financial & Accounting Officer Derivative Exercise and Retained +17,645 – 17,645
16 Feb 2026 Joseph Eiden Other Derivative Acquisition +2,220,000 $1.80 2,220,000
16 Feb 2026 Michelle Robertson Executive VP, CFO, Treasurer and Principal Financial & Accounting Officer Other Derivative Acquisition +1,660,000 $1.80 1,660,000
30 Dec 2025 Robert Jay Spiegel Independent Director Other Acquisition +5,918 $1.32 194,464
14 Dec 2025 James Ziegler Executive Vice President Intent to Sell (Form 144) -20,000 $1.37 –
19 Oct 2025 Ahmed ElNawawi Executive Vice President Other Derivative Acquisition +3,000,000 $1.27 3,000,000
19 Oct 2025 Ahmed ElNawawi Executive Vice President Initial Statement of Beneficial +0 – 10,000
29 Sep 2025 Robert Jay Spiegel Independent Director Other Acquisition +5,702 $1.37 188,546

From Form 4/Form 144 filings. Negative share counts are disposals (sales, gifts, or shares withheld for taxes); positive are acquisitions.

Short interest, by report

Report dateShares short% of floatDays to cover
15 Sep 2026 82,618,677 12.9% 6.7
31 Aug 2026 85,093,515 13.2% 11.0
14 Aug 2026 80,600,696 12.5% 5.8
31 Jul 2026 76,807,284 12.0% 9.9
15 Jul 2026 69,921,486 10.9% 6.8
30 Jun 2026 80,219,249 12.5% 4.7

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