William Blair Investment Management
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William Blair Investment Management’s Ciena CIEN Stock Holding History

William Blair Investment Management’s Portfolio CIEN Stock Details CIEN Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q2 		$65.6M Sell
133,801
-264,778
-66% -$135M 0.2% 137
2026
Q1 		$155M Sell
398,579
-700,014
-64% -$214M 0.51% 52
2025
Q4 		$257M Sell
1,098,593
-1,342,295
-55% -$260M 0.72% 27
2025
Q3 		$356M Sell
2,440,888
-267,652
-10% -$27.3M 0.92% 16
2025
Q2 		$220M Buy
2,708,540
+702,909
+35% +$50.4M 0.58% 36
2025
Q1 		$121M Buy
+2,005,631
New +$159M 0.34% 83
2019
Q2 		– Sell
-472,534
Closed -$17.6M – 379
2019
Q1 		$17.6M Sell
472,534
-48,380
-9% -$1.88M 0.07% 237
2018
Q4 		$17.7M Buy
520,914
+7,636
+1% +$242K 0.09% 208
2018
Q3 		$16M Sell
513,278
-40,768
-7% -$1.14M 0.06% 288
2018
Q2 		$14.7M Buy
+554,046
New +$14.1M 0.05% 289

Other funds holding CIEN

Fidelity Investments
Fidelity Investments Boston, Massachusetts $2.3T AUM 54.33% 1-Year Est. Return
BlackRock
BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return
JP Morgan Chase
JP Morgan Chase New York $1.81T AUM 41.13% 1-Year Est. Return
Vanguard Capital Management
Vanguard Capital Management Malvern, Pennsylvania $4.68T AUM
Vanguard Portfolio Management
Vanguard Portfolio Management Malvern, Pennsylvania $2.22T AUM
State Street
State Street Boston, Massachusetts $3.37T AUM 44.26% 1-Year Est. Return
T. Rowe Price Associates
T. Rowe Price Associates Baltimore, Maryland $999B AUM 46.22% 1-Year Est. Return
Geode Capital Management
Geode Capital Management Boston, Massachusetts $1.88T AUM 44.46% 1-Year Est. Return
American Century Companies
American Century Companies Kansas City, Missouri $226B AUM 44.75% 1-Year Est. Return
Bank of America
Bank of America Charlotte, North Carolina $1.55T AUM 33.47% 1-Year Est. Return

William Blair Investment Management's CIEN Position: Q2 2026 in Review

William Blair Investment Management reduced its Ciena (CIEN) stake by 66% in Q2 2026, selling an estimated $135M and leaving 133,801 shares worth $65.6M. The position accounts for 0.2% of the portfolio, ranked #137.

William Blair Investment Management first reported a position in CIEN in Q2 2018 and has held it in 10 quarters since. The position peaked at $356M in Q3 2025. 1,224 funds tracked by Wall St. Rank hold CIEN as of Q2 2026.

  • William Blair Investment Management held 133,801 shares of Ciena worth $65.6M as of Q2 2026.
  • William Blair Investment Management sold 264,778 Ciena shares in Q2 2026, an estimated $135M.
  • Ciena made up 0.2% of William Blair Investment Management's portfolio in Q2 2026, its #137 holding.
  • William Blair Investment Management first reported a position in Ciena in Q2 2018 and has held it in 10 quarters since.
  • William Blair Investment Management's Ciena position peaked at $356M in Q3 2025.
  • 1,224 funds tracked by Wall St. Rank held Ciena as of Q2 2026.

Based on William Blair Investment Management's 13F filing for Q2 2026, filed 12 Aug 2026.