CIENA CORP (CIEN) Stock Institutional Trading Activity
CIENA CORP (CIEN) position changes reported by tracked institutional filers across multiple SEC 13F reporting periods. Based on recent SEC 13F filings (Q4 2025), investors with some of the largest reported share count changes include Renaissance Technologies LLC, Lone Pine Capital, First Eagle U.S. Value, Mairs & Power Growth Fund, and Sequoia Financial Advisors. Explore insights into buying and selling patterns, position changes, and investment conviction levels to understand institutional trading behavior and market dynamics.
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- CIENA CORP (CIEN) stock institutional ownership
- CIENA CORP (CIEN) stock insider trading activity
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| Portfolio quarter | Name | Type | Quantity | Remaining | Reported stock balance |
|---|---|---|---|---|---|
| Q3 2019 | Renaissance Technologies LLC | Buy | 408,700 | 798,774 | $31,336 |
| Q2 2019 | Renaissance Technologies LLC | Sell | -1,208,200 | 390,074 | $16,044 |
| Q1 2019 | Renaissance Technologies LLC | Buy | 1,318,400 | 1,598,274 | $59,680 |
| Q4 2018 | Renaissance Technologies LLC | Sell | -952,321 | 279,874 | $9,491 |
| Q3 2018 | Renaissance Technologies LLC | Sell | -229,879 | 1,232,195 | $38,494 |
| Q1 2018 | Renaissance Technologies LLC | Sell | -454,300 | 1,462,074 | $37,868 |
| Q4 2017 | Renaissance Technologies LLC | Buy | 1,227,900 | 1,916,374 | $40,110 |
| Q3 2017 | Parnassus Endeavor Fund | Sell | -1,000,000 | 1,700,000 | $37,349 |
| Q2 2017 | Parnassus Endeavor Fund | Sell | -1,800,000 | 2,700,000 | $67,554 |
| Q2 2017 | Renaissance Technologies LLC | Sell | -1,850,500 | 688,474 | $17,226 |
| Q1 2017 | Parnassus Endeavor Fund | Sell | -750,000 | 4,500,000 | $106,245 |
| Q1 2017 | Renaissance Technologies LLC | Sell | -1,493,300 | 2,538,974 | $59,945 |
| Q4 2016 | Parnassus Endeavor Fund | Sell | -450,000 | 5,250,000 | $128,153 |
| Q4 2016 | Renaissance Technologies LLC | Buy | 2,167,574 | 4,032,274 | $98,428 |
| Q3 2016 | Parnassus Endeavor Fund | Sell | -300,000 | 5,700,000 | $124,260 |
| Q3 2016 | Renaissance Technologies LLC | Sell | -12,000 | 1,864,700 | $40,650 |
| Q2 2016 | Parnassus Endeavor Fund | Buy | 400,000 | 6,000,000 | $112,500 |
| Q2 2016 | Renaissance Technologies LLC | Sell | -66,474 | 1,876,700 | $35,188 |
| Q1 2016 | Parnassus Endeavor Fund | Buy | 700,000 | 5,600,000 | $106,512 |
| Q1 2016 | Renaissance Technologies LLC | Sell | -55,200 | 1,943,174 | $36,959 |
| Q4 2015 | Parnassus Endeavor Fund | Buy | 1,800,000 | 4,900,000 | $101,381 |
| Q4 2015 | Renaissance Technologies LLC | Buy | 1,771,490 | 1,998,374 | $41,346 |
| Q3 2015 | Parnassus Endeavor Fund | Buy | 100,000 | 3,100,000 | $64,232 |
| Q3 2015 | Renaissance Technologies LLC | Sell | -136,421 | 226,884 | $4,701 |
| Q2 2015 | Parnassus Endeavor Fund | Sell | -625,000 | 3,000,000 | $71,040 |
| Q2 2015 | Renaissance Technologies LLC | Buy | 315,105 | 363,305 | $8,603 |
| Q1 2015 | Parnassus Endeavor Fund | Sell | -100,000 | 3,625,000 | $69,999 |
| Q1 2015 | Renaissance Technologies LLC | Buy | 30,695 | 48,200 | $931 |
| Q4 2014 | Parnassus Endeavor Fund | Buy | 1,385,000 | 3,725,000 | $72,302 |
| Q4 2014 | Renaissance Technologies LLC | Sell | -1,651,000 | 17,505 | $340 |
Frequently asked questions about CIEN activity
Which institutional owners are buying CIEN?
Institutional owners buying CIEN include investors who have either initiated new positions or increased their existing holdings based on recent SEC 13F filings. The activity table above highlights which funds added shares in the latest reporting periods and how their positions changed over time.
What does "buy" mean in CIEN activity?
"Buy" means an investor increased their reported position in CIEN compared to the prior reporting period. This reflects growing exposure to CIENA CORP (CIEN) rather than necessarily a brand-new position (though new positions also appear as buys when prior quantity was zero).
Is institutional interest in CIEN increasing?
Institutional interest in CIEN can be assessed by comparing the number of tracked funds adding or increasing positions versus those trimming or exiting across the periods shown. A higher number of additions typically signals increasing participation among large filers, but it should be read alongside position sizes and the full table.