DOSSIER · 13F Holders · Q3 2026

SELLAS LIFE SCIENCES GROUP I

6 institutions still hold SELLAS LIFE SCIENCES GROUP I as of Q3 2026. Tracked across SEC 13F-HR filings, with insider and 13D/G activity surfaced alongside.

CUSIP 81642T909·6 13F holders·last filed Sep 30, 2026
Market cap
—
13F value held
$85M
visible holders
Holders
6
filers reporting
Concentration
69.45%
GROUP ONE TRADING LLC #1
top holder share
AI Holders Summary · Q3 2026

6 institutions reported SELLAS LIFE SCIENCES GROUP I in Q3 2026. GROUP ONE TRADING LLC leads at 69.4% of the visible book.

Top holders

Sorted by position value. Source: SEC EDGAR 13F-HR filings.

#HolderValueShares% port.Quarter
01
GROUP ONE TRADING LLC
CIK 0000932540
$59M4.8M0.08%Q3 2026
02
SIMPLEX TRADING, LLC
CIK 0001488542
$17M1.4M0.01%Q3 2026
03
IMC-Chicago, LLC
CIK 0001452861· Market maker
$5M385K0.00%Q3 2026
04
HRT FINANCIAL LP
CIK 0001475597
$4M301K0.01%Q3 2026
05
Marathon Trading Investment Management LLC
CIK 0001572748
$617K50K0.02%Q3 2026
06
CONCOURSE FINANCIAL GROUP SECURITIES, INC.
CIK 0000752798
$00—Q2 2025