Century Aluminum Company
US ˙ NasdaqGS ˙ US1564311082

SecurityCENX / Century Aluminum Company
InstitutionSei Investments Co
Latest Disclosed Ownership52,852 shares
Latest Disclosed Value $ 2,070,872
Sei Investments Co reports 35.84% decrease in ownership of CENX / Century Aluminum Company

On February 13, 2026 - Sei Investments Co filed a 13F-HR form disclosing ownership of 52,852 shares of Century Aluminum Company (US:CENX) valued at $2,070,741 USD as of December 31, 2025. The entity filed a previous 13F-HR on November 13, 2025 disclosing 82,373 shares of Century Aluminum Company. This represents a change in shares of -35.84% during the quarter. The current value of the position is $3,542,934 USD.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

Upgrade to unlock premium data and export to Excel .

Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-02-13 2025-12-31 13F CENTURY ALUM COM 156431108 52,852 -29,521 -35.84 2,071 -14.39
2025-11-13 2025-09-30 13F CENTURY ALUM COM 156431108 82,373 61,447 293.64 2,419 541.38 0.0026
2025-08-14 2025-06-30 13F CENTURY ALUM COM 156431108 20,926 -2,664 -11.29 377 -13.73 0.0004
2025-05-14 2025-03-31 13F/A-1 CENTURY ALUM COM 156431108 23,590 3,173 15.54 438 17.79 0.0006
2025-05-13 2025-03-31 13F CENTURY ALUM COM 156431108 20,417 0 372 0.0004
2025-02-11 2024-12-31 13F CENTURY ALUM COM 156431108 20,417 20,417 372 0.0005
2024-11-12 2024-09-30 13F CENTURY ALUM COM 156431108 0 -24,849 -100.00 0 -100.00
2024-08-13 2024-06-30 13F CENTURY ALUM COM 156431108 24,849 24,849 416 0.0006
2023-02-10 2022-12-31 13F CENTURY ALUM COM 156431108 0 -24,878 -100.00 0 -100.00
2022-11-14 2022-09-30 13F CENTURY ALUM COM 156431108 24,878 -6,776 -21.41 131 -42.04 0.0003
2022-08-15 2022-06-30 13F CENTURY ALUM COM 156431108 31,654 -15,778 -33.26 226 -82.23 0.0005
2022-05-13 2022-03-31 13F CENTURY ALUM COM 156431108 47,432 29,877 170.19 1,272 302.53 0.0026
2022-02-14 2021-12-31 13F CENTURY ALUM COM 156431108 17,555 -199 -1.12 316 34.47 0.0006
2021-11-12 2021-09-30 13F CENTURY ALUM COM 156431108 17,754 727 4.27 235 25.00 0.0005
2021-08-06 2021-06-30 13F CENTURY ALUM COM 156431108 17,027 17,027 188 0.0004
2020-12-04 2020-09-30 13F/A-1 CENTURY ALUM COM 156431108 0 -50,395 -100.00 0 -100.00
2020-08-17 2020-06-30 13F/A-1 CENTURY ALUM COM 156431108 50,395 88 0.17 361 100.56 0.0011
2020-08-11 2020-06-30 13F CENTURY ALUM COM 156431108 55,037 4,730 415 1,125.7096
2020-05-14 2020-03-31 13F CENTURY ALUM COM 156431108 50,307 -4,367 -7.99 180 -55.88 0.0007
2020-02-06 2019-12-31 13F CENTURY ALUM COM 156431108 54,674 3,937 7.76 408 22.16 0.0012
2019-11-12 2019-09-30 13F CENTURY ALUM COM 156431108 50,737 9,987 24.51 334 19.71 0.0009
2019-08-14 2019-06-30 13F CENTURY ALUM COM 156431108 40,750 30,352 291.90 279 206.59 0.0009
2019-05-15 2019-03-31 13F CENTURY ALUM COM 156431108 10,398 8,876 583.18 91 405.56 0.0003
2019-02-13 2018-12-31 13F CENTURY ALUM COM 156431108 1,522 -58 -3.67 18 0.00 0.0001
2018-11-08 2018-09-30 13F CENTURY ALUM COM 156431108 1,580 28 1.80 18 -25.00 0.0001
2018-08-03 2018-06-30 13F CENTURY ALUM COM 156431108 1,552 0 0.00 24 -7.69 0.0001
2018-05-11 2018-03-31 13F CENTURY ALUM COM 156431108 1,552 30 1.97 26 -13.33 0.0001
2018-02-08 2017-12-31 13F CENTURY ALUM COM 156431108 1,522 -108,096 -98.61 30 -98.35 0.0001
2017-11-06 2017-09-30 13F CENTURY ALUM COM 156431108 109,618 -5,835 -5.05 1,817 1.00 0.0065
2017-07-31 2017-06-30 13F CENTURY ALUM COM 156431108 115,453 5,380 4.89 1,799 28.78 0.0072
2017-05-05 2017-03-31 13F CENTURY ALUM COM 156431108 110,073 -43,355 -28.26 1,397 6.40 0.0061
2017-02-02 2016-12-31 13F CENTURY ALUM COM 156431108 153,428 -68,163 -30.76 1,313 -14.74 0.0064
2016-11-04 2016-09-30 13F CENTURY ALUM COM 156431108 221,591 79,484 55.93 1,540 71.11 0.0078
2016-08-11 2016-06-30 13F CENTURY ALUM COM 156431108 142,107 92,879 188.67 900 159.37 0.0054
2016-05-10 2016-03-31 13F/A-1 CENTURY ALUM COM 156431108 49,228 45,279 1,146.59 347 1,941.18 0.0022
2016-02-03 2015-12-31 13F CENTURY ALUM COM 156431108 3,949 3,949 -91.98 17 -95.10 0.0001
2015-08-04 2015-06-30 13F CENTURY ALUM COM 156431108 0 -3,970 -100.00 0 -100.00
2015-05-14 2015-03-31 13F/A-1 CENTURY ALUM COM 156431108 3,970 -3,210 -44.71 55 -68.57 0.0005
2015-05-01 2015-03-31 13F CENTRAL FED COM NEW 156431108 3,970 55
2015-02-10 2014-12-31 13F CENTURY ALUM COM 156431108 7,180 7,180 175 0.0015
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.