William Blair & Company
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William Blair & Company’s SELLAS Life Sciences SLS Stock Holding History

William Blair & Company’s Portfolio SLS Stock Details SLS Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q2 		$252K Buy
17,106
+3,101
+22% +$21.4K ﹤0.01% 1488
2026
Q1 		$59.2K Sell
14,005
-11,997
-46% -$53.7K ﹤0.01% 1675
2025
Q4 		$98K Buy
26,002
+10,000
+62% +$19.4K ﹤0.01% 1566
2025
Q3 		$25.8K Hold
16,002
– – ﹤0.01% 1700
2025
Q2 		$35K Buy
+16,002
New +$24.6K ﹤0.01% 1639

Other funds holding SLS

BlackRock
BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return
State Street
State Street Boston, Massachusetts $3.38T AUM 44.17% 1-Year Est. Return
Vanguard Capital Management
Vanguard Capital Management Malvern, Pennsylvania $4.68T AUM
Geode Capital Management
Geode Capital Management Boston, Massachusetts $1.88T AUM 44.46% 1-Year Est. Return
AFM
Anson Funds Management Dallas, Texas $1.68B AUM 373.57% 1-Year Est. Return
Vanguard Portfolio Management
Vanguard Portfolio Management Malvern, Pennsylvania $2.22T AUM
Susquehanna International Group
Susquehanna International Group Bala Cynwyd, Pennsylvania $1.28T AUM 58.89% 1-Year Est. Return
Jones Financial Companies
Jones Financial Companies Des Peres, Missouri $250B AUM 21.32% 1-Year Est. Return
Northern Trust
Northern Trust Chicago, Illinois $860B AUM 41.15% 1-Year Est. Return
Vanguard Fiduciary Trust
Vanguard Fiduciary Trust Malvern, Pennsylvania $454B AUM

William Blair & Company's SLS Position: Q2 2026 in Review

William Blair & Company increased its SELLAS Life Sciences (SLS) stake by 22% in Q2 2026, buying an estimated $21.4K and bringing the position to 17,106 shares worth $252K. The position accounts for ﹤0.01% of the portfolio, ranked #1488.

William Blair & Company first reported a position in SLS in Q2 2025 and has held it in 5 quarters since. 193 funds tracked by Wall St. Rank hold SLS as of Q2 2026.

  • William Blair & Company held 17,106 shares of SELLAS Life Sciences worth $252K as of Q2 2026.
  • William Blair & Company bought 3,101 SELLAS Life Sciences shares in Q2 2026, an estimated $21.4K.
  • SELLAS Life Sciences made up ﹤0.01% of William Blair & Company's portfolio in Q2 2026, its #1488 holding.
  • William Blair & Company first reported a position in SELLAS Life Sciences in Q2 2025 and has held it in 5 quarters since.
  • 193 funds tracked by Wall St. Rank held SELLAS Life Sciences as of Q2 2026.

Based on William Blair & Company's 13F filing for Q2 2026, filed 11 Aug 2026.