Century Aluminum Company
US ˙ NasdaqGS ˙ US1564311082

SecurityCENX / Century Aluminum Company
InstitutionCitigroup Inc
Latest Disclosed Ownership26,272 shares
Latest Disclosed Value $ 1,541,904
Citigroup Inc ownership in CENX / Century Aluminum Company

On May 11, 2026 - Citigroup Inc filed a 13F-HR form disclosing ownership of 26,272 shares of Century Aluminum Company (US:CENX) valued at $1,541,904 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 26,383 shares of Century Aluminum Company. This represents a change in shares of -0.42% during the quarter. The current value of the position is $1,744,855 USD.

Citigroup Inc has a history of taking positions in derivatives of the underlying security (CENX) in the form of stock options. The firm currently holds call options representing 0 of underlying shares valued at $0 USD and put options representing 0 of underlying shares valued at $0 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

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.

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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

CENX / Century Aluminum Company Historical Put/Call Ratio
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)
2026-05-11 2026-03-31 13F CENTURY ALUM COM 156431108 26,272 -111 -0.42 1,542 49.18 0.0003
2026-02-13 2025-12-31 13F CENTURY ALUM COM 156431108 26,383 9,534 56.58 1,034 109.11 0.0005
2025-11-10 2025-09-30 13F CENTURY ALUM COM 156431108 16,849 -29,184 -63.40 495 -40.41 0.0002
2025-08-11 2025-06-30 13F CENTURY ALUM COM 156431108 46,033 -38,184 -45.34 830 -46.96 0.0004
2025-05-12 2025-03-31 13F CENTURY ALUM COM 156431108 84,217 12,299 17.10 1,563 19.31 0.0008
2025-02-12 2024-12-31 13F CENTURY ALUM COM 156431108 71,918 5,739 8.67 1,310 21.97 0.0008
2024-11-12 2024-09-30 13F CENTURY ALUM COM 156431108 66,179 29,876 82.30 1,074 76.64 0.0006
2024-08-12 2024-06-30 13F CENTURY ALUM COM 156431108 36,303 -187 -0.51 608 8.38 0.0004
2024-05-10 2024-03-31 13F CENTURY ALUM COM 156431108 36,490 4,386 13.66 562 44.22 0.0004
2024-02-09 2023-12-31 13F CENTURY ALUM COM 156431108 32,104 10,591 49.23 390 152.60 0.0003
2023-12-06 2023-09-30 13F/A-1 CENTURY ALUM COM 156431108 21,513 -17,707 -45.15 155 -54.84 0.0001
2023-11-09 2023-09-30 13F CENTURY ALUM COM 156431108 21,513 -17,707 155 0.0001
2023-08-10 2023-06-30 13F CENTURY ALUM COM 156431108 39,220 14,144 56.40 342 36.40 0.0002
2023-05-11 2023-03-31 13F CENTURY ALUM COM 156431108 25,076 -5,606 -18.27 251 0.00 0.0002
2023-02-09 2022-12-31 13F CENTURY ALUM COM 156431108 30,682 3,578 13.20 251 74.83 0.0002
2022-11-10 2022-09-30 13F CENTURY ALUM COM 156431108 27,104 304 1.13 143 -27.78 0.0001
2022-08-10 2022-06-30 13F CENTURY ALUM COM 156431108 26,800 -20,834 -43.74 198 -84.20 0.0001
2022-05-12 2022-03-31 13F CENTURY ALUM COM 156431108 47,634 -1,079 -2.22 1,253 55.27 0.0008
2022-02-10 2021-12-31 13F CENTURY ALUM COM 156431108 48,713 7,200 17.34 807 44.36 0.0004
2021-11-10 2021-09-30 13F CENTURY ALUM COM 156431108 41,513 -15,798 -27.57 559 -24.25 0.0003
2021-08-10 2021-06-30 13F CENTURY ALUM COM 156431108 57,311 25,120 78.03 738 29.93 0.0004
2021-05-13 2021-03-31 13F CENTURY ALUM COM 156431108 32,191 17,071 112.90 568 240.12 0.0004
2021-02-11 2020-12-31 13F CENTURY ALUM COM 156431108 15,120 7,010 86.44 167 187.93 0.0001
2020-11-12 2020-09-30 13F CENTURY ALUM COM 156431108 8,110 -11,805 -59.28 58 -59.15 0.0000
2020-08-12 2020-06-30 13F CENTURY ALUM COM 156431108 19,915 -1,730 -7.99 142 82.05 0.0001
2020-05-12 2020-03-31 13F CENTURY ALUM COM 156431108 21,645 -5,154 -19.23 78 -61.19 0.0001
2020-02-12 2019-12-31 13F CENTURY ALUM COM 156431108 26,799 -184,288 -87.30 201 -85.64 0.0001
2019-11-08 2019-09-30 13F CENTURY ALUM COM 156431108 211,087 5,930 2.89 1,400 -1.20 0.0011
2019-08-12 2019-06-30 13F CENTURY ALUM COM 156431108 205,157 15,019 7.90 1,417 -16.10 0.0011
2019-05-13 2019-03-31 13F CENTURY ALUM COM 156431108 190,138 174,132 1,087.92 1,689 1,343.59 0.0016
2019-02-12 2018-12-31 13F CENTURY ALUM COM 156431108 16,006 -55,721 -77.68 117 -86.38 0.0001
2018-11-13 2018-09-30 13F CENTURY ALUM COM 156431108 71,727 68,738 2,299.70 859 1,727.66 0.0008
2018-08-10 2018-06-30 13F CENTURY ALUM COM 156431108 2,989 -16,186 -84.41 47 -85.17 0.0000
2018-05-11 2018-03-31 13F CENTURY ALUM COM 156431108 19,175 -1,254 -6.14 317 -21.14 0.0003
2018-02-12 2017-12-31 13F CENTURY ALUM COM 156431108 20,429 -10,395 -33.72 402 -21.33 0.0003
2017-11-13 2017-09-30 13F CENTURY ALUM COM 156431108 30,824 -15,564 -33.55 511 -29.32 0.0004
2017-08-11 2017-06-30 13F CENTURY ALUM COM 156431108 46,388 -3,385 -6.80 723 14.58 0.0007
2017-05-12 2017-03-31 13F CENTURY ALUM COM 156431108 49,773 -48,094 -49.14 631 -24.70 0.0006
2017-02-10 2016-12-31 13F CENTURY ALUM COM 156431108 97,867 50,516 106.68 838 155.49 0.0008
2016-11-10 2016-09-30 13F CENTURY ALUM COM 156431108 47,351 15,534 48.82 328 62.38 0.0003
2016-08-12 2016-06-30 13F CENTURY ALUM COM 156431108 31,817 -24,491 -43.49 202 -49.25 0.0002
2016-05-13 2016-03-31 13F CENTURY ALUM COM 156431108 56,308 16,190 40.36 398 124.86 0.0004
2016-02-12 2015-12-31 13F CENTURY ALUM COM 156431108 40,118 4,978 14.17 177 9.94 0.0002
2015-11-13 2015-09-30 13F CENTURY ALUM COM 156431108 35,140 15,556 79.43 161 -21.08 0.0002
2015-08-13 2015-06-30 13F CENTURY ALUM COM 156431108 19,584 -30,868 -61.18 204 -70.73 0.0002
2015-05-14 2015-03-31 13F CENTURY ALUM COM 156431108 50,452 -15,723 -23.76 697 -56.84 0.0007
2015-02-17 2014-12-31 13F CENTURY ALUM COM 156431108 66,175 22,144 50.29 1,615 41.17 0.0014
2014-11-14 2014-09-30 13F CENTURY ALUM COM 156431108 44,031 17,318 64.83 1,144 173.03 0.0010
2014-08-14 2014-06-30 13F CENTURY ALUM COM 156431108 26,713 -11,963 -30.93 419 -18.00 0.0004
2014-05-15 2014-03-31 13F CENTURY ALUM COM 156431108 38,676 -20,560 -34.71 511 -17.45 0.0005
2014-02-14 2013-12-31 13F CENTURY ALUM COM 156431108 59,236 19,022 47.30 619 91.05 0.0006
2013-11-14 2013-09-30 13F CENTURY ALUM COM 156431108 40,214 -622 -1.52 324 -14.51 0.0003
2013-08-14 2013-06-30 13F CENTURY ALUM COM 156431108 40,836 40,836 379 0.0004
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2015-11-13 2015-09-30 13F CENTURY ALUM COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2015-08-13 2015-06-30 13F CENTURY ALUM COM Call 200 -66.67 2 -66.67 n/a n/a n/a
2014-02-14 2013-12-31 13F CENTURY ALUM COM Call 600 0.00 6 20.00 n/a n/a n/a
2013-11-14 2013-09-30 13F CENTURY ALUM COM Call 600 0.00 5 -16.67 n/a n/a n/a
2013-08-14 2013-06-30 13F CENTURY ALUM COM Call 600 6 n/a n/a n/a
Disclosed Put Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share Price Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2014-05-15 2014-03-31 13F CENTURY ALUM COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2014-02-14 2013-12-31 13F CENTURY ALUM COM Put 1,300 0.00 14 40.00 n/a n/a n/a
2013-11-14 2013-09-30 13F CENTURY ALUM COM Put 1,300 0.00 10 -16.67 n/a n/a n/a
2013-08-14 2013-06-30 13F CENTURY ALUM COM Put 1,300 12 n/a n/a n/a
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.