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
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

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VPM
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Morgan Stanley
Morgan Stanley New York $1.66T AUM 25.57% 1-Year Est. Return
Northern Trust
Northern Trust Chicago, Illinois $757B AUM 28.64% 1-Year Est. Return
VFT
Vanguard Fiduciary Trust Malvern, Pennsylvania $396B AUM

William Blair & Company's SLS Position: Q1 2026 in Review

William Blair & Company reduced its SELLAS Life Sciences (SLS) stake by 46% in Q1 2026, selling an estimated $53.7K and leaving 14,005 shares worth $59.2K. The position accounts for ﹤0.01% of the portfolio, ranked #1675.

William Blair & Company first reported a position in SLS in Q2 2025 and has held it in 4 quarters since. The position peaked at $98K in Q4 2025. 160 funds tracked by Wall St. Rank hold SLS as of Q1 2026.

  • William Blair & Company held 14,005 shares of SELLAS Life Sciences worth $59.2K as of Q1 2026.
  • William Blair & Company sold 11,997 SELLAS Life Sciences shares in Q1 2026, an estimated $53.7K.
  • SELLAS Life Sciences made up ﹤0.01% of William Blair & Company's portfolio in Q1 2026, its #1675 holding.
  • William Blair & Company first reported a position in SELLAS Life Sciences in Q2 2025 and has held it in 4 quarters since.
  • William Blair & Company's SELLAS Life Sciences position peaked at $98K in Q4 2025.
  • 160 funds tracked by Wall St. Rank held SELLAS Life Sciences as of Q1 2026.

Based on William Blair & Company's 13F filing for Q1 2026, filed 8 May 2026.