Amkor Technology, Inc.
MX ˙ BMV ˙ US0316521006
SecurityMX:AMKR / Amkor Technology, Inc.
InstitutionCitigroup Inc
Latest Disclosed Ownership132,050 shares
Latest Disclosed Value $ 5,946,212
Citigroup Inc ownership in AMKR / Amkor Technology, Inc.

On May 11, 2026 - Citigroup Inc filed a 13F-HR form disclosing ownership of 132,050 shares of Amkor Technology, Inc. (MX:AMKR) valued at $5,946,212 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 55,077 shares of Amkor Technology, Inc.. This represents a change in shares of 139.76% during the quarter.

Citigroup Inc has a history of taking positions in derivatives of the underlying security (AMKR) 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.

MX:AMKR / Amkor Technology, Inc. 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 AMKOR TECHNOLOGY COM 031652100 132,050 76,973 139.76 5,946 173.51 0.0013
2026-02-13 2025-12-31 13F AMKOR TECHNOLOGY COM 031652100 55,077 -975 -1.74 2,174 36.64 0.0010
2025-11-10 2025-09-30 13F AMKOR TECHNOLOGY COM 031652100 56,052 -107,942 -65.82 1,592 -53.78 0.0007
2025-08-11 2025-06-30 13F AMKOR TECHNOLOGY COM 031652100 163,994 -2,677 -1.61 3,442 14.35 0.0017
2025-05-12 2025-03-31 13F AMKOR TECHNOLOGY COM 031652100 166,671 32,895 24.59 3,010 -12.40 0.0015
2025-02-12 2024-12-31 13F AMKOR TECHNOLOGY COM 031652100 133,776 17,153 14.71 3,437 -3.70 0.0020
2024-11-12 2024-09-30 13F AMKOR TECHNOLOGY COM 031652100 116,623 -24,878 -17.58 3,569 -36.98 0.0021
2024-08-12 2024-06-30 13F AMKOR TECHNOLOGY COM 031652100 141,501 24,790 21.24 5,663 50.51 0.0036
2024-05-10 2024-03-31 13F AMKOR TECHNOLOGY COM 031652100 116,711 18,916 19.34 3,763 15.65 0.0025
2024-02-09 2023-12-31 13F AMKOR TECHNOLOGY COM 031652100 97,795 23,780 32.13 3,254 94.56 0.0023
2023-12-06 2023-09-30 13F/A-1 AMKOR TECHNOLOGY COM 031652100 74,015 -505 -0.68 1,673 -24.55 0.0013
2023-11-09 2023-09-30 13F AMKOR TECHNOLOGY COM 031652100 74,015 -505 1,673 0.0012
2023-08-10 2023-06-30 13F AMKOR TECHNOLOGY COM 031652100 74,520 24,600 49.28 2,217 70.72 0.0015
2023-05-11 2023-03-31 13F AMKOR TECHNOLOGY COM 031652100 49,920 14,119 39.44 1,299 51.28 0.0009
2023-02-09 2022-12-31 13F AMKOR TECHNOLOGY COM 031652100 35,801 -753 -2.06 859 37.72 0.0007
2022-11-10 2022-09-30 13F AMKOR TECHNOLOGY COM 031652100 36,554 -75,918 -67.50 623 -67.33 0.0004
2022-08-10 2022-06-30 13F AMKOR TECHNOLOGY COM 031652100 112,472 7,207 6.85 1,907 -16.58 0.0014
2022-05-12 2022-03-31 13F AMKOR TECHNOLOGY COM 031652100 105,265 -13,736 -11.54 2,286 -22.51 0.0014
2022-02-10 2021-12-31 13F AMKOR TECHNOLOGY COM 031652100 119,001 33,159 38.63 2,950 37.72 0.0016
2021-11-10 2021-09-30 13F AMKOR TECHNOLOGY COM 031652100 85,842 40,487 89.27 2,142 99.44 0.0013
2021-08-10 2021-06-30 13F AMKOR TECHNOLOGY COM 031652100 45,355 -99,332 -68.65 1,074 -68.70 0.0006
2021-05-13 2021-03-31 13F AMKOR TECHNOLOGY COM 031652100 144,687 61,356 73.63 3,431 172.95 0.0022
2021-02-11 2020-12-31 13F AMKOR TECHNOLOGY COM 031652100 83,331 283 0.34 1,257 35.02 0.0007
2020-11-12 2020-09-30 13F AMKOR TECHNOLOGY COM 031652100 83,048 -9,326 -10.10 931 -18.12 0.0006
2020-08-12 2020-06-30 13F AMKOR TECHNOLOGY COM 031652100 92,374 -107,983 -53.90 1,137 -27.16 0.0009
2020-05-12 2020-03-31 13F AMKOR TECHNOLOGY COM 031652100 200,357 167,885 517.01 1,561 269.91 0.0014
2020-02-12 2019-12-31 13F AMKOR TECHNOLOGY COM 031652100 32,472 16,612 104.74 422 193.06 0.0003
2019-11-08 2019-09-30 13F AMKOR TECHNOLOGY COM 031652100 15,860 -34,395 -68.44 144 -61.60 0.0001
2019-08-12 2019-06-30 13F AMKOR TECHNOLOGY COM 031652100 50,255 42,379 538.08 375 459.70 0.0003
2019-05-13 2019-03-31 13F AMKOR TECHNOLOGY COM 031652100 7,876 -115,265 -93.60 67 -91.71 0.0001
2019-02-12 2018-12-31 13F AMKOR TECHNOLOGY COM 031652100 123,141 112,995 1,113.69 808 977.33 0.0008
2018-11-13 2018-09-30 13F AMKOR TECHNOLOGY COM 031652100 10,146 -89,747 -89.84 75 -91.26 0.0001
2018-08-10 2018-06-30 13F AMKOR TECHNOLOGY COM 031652100 99,893 10,314 11.51 858 -5.40 0.0008
2018-05-11 2018-03-31 13F AMKOR TECHNOLOGY COM 031652100 89,579 54,002 151.79 907 154.06 0.0007
2018-02-12 2017-12-31 13F AMKOR TECHNOLOGY COM 031652100 35,577 28,557 406.79 357 382.43 0.0003
2017-11-13 2017-09-30 13F AMKOR TECHNOLOGY COM 031652100 7,020 -34,901 -83.25 74 -81.91 0.0001
2017-08-11 2017-06-30 13F AMKOR TECHNOLOGY COM 031652100 41,921 9,629 29.82 409 9.36 0.0004
2017-05-12 2017-03-31 13F AMKOR TECHNOLOGY COM 031652100 32,292 -99,422 -75.48 374 -73.07 0.0003
2017-02-10 2016-12-31 13F AMKOR TECHNOLOGY COM 031652100 131,714 92,243 233.70 1,389 261.72 0.0013
2016-11-10 2016-09-30 13F AMKOR TECHNOLOGY COM 031652100 39,471 -43,364 -52.35 384 -19.33 0.0004
2016-08-12 2016-06-30 13F AMKOR TECHNOLOGY COM 031652100 82,835 -98,380 -54.29 476 -55.43 0.0005
2016-05-13 2016-03-31 13F AMKOR TECHNOLOGY COM 031652100 181,215 58,853 48.10 1,068 43.74 0.0012
2016-02-12 2015-12-31 13F AMKOR TECHNOLOGY COM 031652100 122,362 36,117 41.88 743 91.99 0.0007
2015-11-13 2015-09-30 13F AMKOR TECHNOLOGY COM 031652100 86,245 -44,543 -34.06 387 -50.57 0.0004
2015-08-13 2015-06-30 13F AMKOR TECHNOLOGY COM 031652100 130,788 -16,754 -11.36 783 -39.95 0.0007
2015-05-14 2015-03-31 13F AMKOR TECHNOLOGY COM 031652100 147,542 -83,241 -36.07 1,304 -20.44 0.0013
2015-02-17 2014-12-31 13F AMKOR TECHNOLOGY COM 031652100 230,783 60,460 35.50 1,639 14.38 0.0015
2014-11-14 2014-09-30 13F AMKOR TECHNOLOGY COM 031652100 170,323 30,490 21.80 1,433 -8.32 0.0013
2014-08-14 2014-06-30 13F AMKOR TECHNOLOGY COM 031652100 139,833 -70,157 -33.41 1,563 8.54 0.0015
2014-05-15 2014-03-31 13F AMKOR TECHNOLOGY COM 031652100 209,990 39,636 23.27 1,440 37.93 0.0015
2014-02-14 2013-12-31 13F AMKOR TECHNOLOGY COM 031652100 170,354 -68,784 -28.76 1,044 1.66 0.0009
2013-11-14 2013-09-30 13F AMKOR TECHNOLOGY COM 031652100 239,138 73,249 44.16 1,027 47.13 0.0010
2013-08-14 2013-06-30 13F AMKOR TECHNOLOGY COM 031652100 165,889 165,889 698 0.0007
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
(%)
2025-02-12 2024-12-31 13F AMKOR TECHNOLOGY COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2024-11-12 2024-09-30 13F AMKOR TECHNOLOGY COM Call 7,600 233 n/a n/a n/a
2021-02-11 2020-12-31 13F AMKOR TECHNOLOGY COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2020-11-12 2020-09-30 13F AMKOR TECHNOLOGY COM Call 6,100 -66.67 68 -69.78 n/a n/a n/a
2020-08-12 2020-06-30 13F AMKOR TECHNOLOGY COM Call 18,300 -50.81 225 -22.41 n/a n/a n/a
2020-05-12 2020-03-31 13F AMKOR TECHNOLOGY COM Call 37,200 463.64 290 237.21 n/a n/a n/a
2020-02-12 2019-12-31 13F AMKOR TECHNOLOGY COM Call 6,600 -56.29 86 -37.23 n/a n/a n/a
2019-11-08 2019-09-30 13F AMKOR TECHNOLOGY COM Call 15,100 344.12 137 448.00 n/a n/a n/a
2019-08-12 2019-06-30 13F AMKOR TECHNOLOGY COM Call 3,400 -49.25 25 -56.14 n/a n/a n/a
2019-05-13 2019-03-31 13F AMKOR TECHNOLOGY COM Call 6,700 13.56 57 46.15 n/a n/a n/a
2019-02-12 2018-12-31 13F AMKOR TECHNOLOGY COM Call 5,900 5.36 39 -4.88 n/a n/a n/a
2018-11-13 2018-09-30 13F AMKOR TECHNOLOGY COM Call 5,600 -39.13 41 -48.10 n/a n/a n/a
2018-08-10 2018-06-30 13F AMKOR TECHNOLOGY COM Call 9,200 76.92 79 49.06 n/a n/a n/a
2018-05-11 2018-03-31 13F AMKOR TECHNOLOGY COM Call 5,200 33.33 53 35.90 n/a n/a n/a
2018-02-12 2017-12-31 13F AMKOR TECHNOLOGY COM Call 3,900 -61.39 39 -63.55 n/a n/a n/a
2017-11-13 2017-09-30 13F AMKOR TECHNOLOGY COM Call 10,100 -9.01 107 -0.93 n/a n/a n/a
2017-08-11 2017-06-30 13F AMKOR TECHNOLOGY COM Call 11,100 -83.91 108 -86.50 n/a n/a n/a
2017-05-12 2017-03-31 13F AMKOR TECHNOLOGY COM Call 69,000 484.75 800 545.16 n/a n/a n/a
2017-02-10 2016-12-31 13F AMKOR TECHNOLOGY COM Call 11,800 28.26 124 39.33 n/a n/a n/a
2016-11-10 2016-09-30 13F AMKOR TECHNOLOGY COM Call 9,200 -11.54 89 48.33 n/a n/a n/a
2016-08-12 2016-06-30 13F AMKOR TECHNOLOGY COM Call 10,400 -14.75 60 -16.67 n/a n/a n/a
2016-05-13 2016-03-31 13F AMKOR TECHNOLOGY COM Call 12,200 -56.27 72 -57.65 n/a n/a n/a
2016-02-12 2015-12-31 13F AMKOR TECHNOLOGY COM Call 27,900 146.90 170 233.33 n/a n/a n/a
2015-11-13 2015-09-30 13F AMKOR TECHNOLOGY COM Call 11,300 29.89 51 -1.92 n/a n/a n/a
2015-08-13 2015-06-30 13F AMKOR TECHNOLOGY COM Call 8,700 -31.50 52 -53.57 n/a n/a n/a
2015-05-14 2015-03-31 13F AMKOR TECHNOLOGY COM Call 12,700 -31.35 112 -14.50 n/a n/a n/a
2015-02-17 2014-12-31 13F AMKOR TECHNOLOGY COM Call 18,500 -78.74 131 -82.10 n/a n/a n/a
2014-11-14 2014-09-30 13F AMKOR TECHNOLOGY COM Call 87,000 -16.91 732 -37.49 n/a n/a n/a
2014-08-14 2014-06-30 13F AMKOR TECHNOLOGY COM Call 104,700 1,013.83 1,171 1,729.69 n/a n/a n/a
2014-05-15 2014-03-31 13F AMKOR TECHNOLOGY COM Call 9,400 51.61 64 68.42 n/a n/a n/a
2014-02-14 2013-12-31 13F AMKOR TECHNOLOGY COM Call 6,200 226.32 38 375.00 n/a n/a n/a
2013-11-14 2013-09-30 13F AMKOR TECHNOLOGY COM Call 1,900 -93.04 8 -93.04 n/a n/a n/a
2013-08-14 2013-06-30 13F AMKOR TECHNOLOGY COM Call 27,300 115 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
(%)
2021-02-11 2020-12-31 13F AMKOR TECHNOLOGY COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2020-11-12 2020-09-30 13F AMKOR TECHNOLOGY COM Put 400 -93.75 4 -94.94 n/a n/a n/a
2020-08-12 2020-06-30 13F AMKOR TECHNOLOGY COM Put 6,400 -92.59 79 -88.26 n/a n/a n/a
2020-05-12 2020-03-31 13F AMKOR TECHNOLOGY COM Put 86,400 1,778.26 673 1,021.67 n/a n/a n/a
2020-02-12 2019-12-31 13F AMKOR TECHNOLOGY COM Put 4,600 -66.91 60 -52.38 n/a n/a n/a
2019-11-08 2019-09-30 13F AMKOR TECHNOLOGY COM Put 13,900 -65.59 126 -58.14 n/a n/a n/a
2019-08-12 2019-06-30 13F AMKOR TECHNOLOGY COM Put 40,400 3.32 301 -9.88 n/a n/a n/a
2019-05-13 2019-03-31 13F AMKOR TECHNOLOGY COM Put 39,100 49.81 334 95.32 n/a n/a n/a
2019-02-12 2018-12-31 13F AMKOR TECHNOLOGY COM Put 26,100 -0.76 171 -11.86 n/a n/a n/a
2018-11-13 2018-09-30 13F AMKOR TECHNOLOGY COM Put 26,300 298.48 194 240.35 n/a n/a n/a
2018-08-10 2018-06-30 13F AMKOR TECHNOLOGY COM Put 6,600 200.00 57 159.09 n/a n/a n/a
2018-05-11 2018-03-31 13F AMKOR TECHNOLOGY COM Put 2,200 -78.43 22 -78.64 n/a n/a n/a
2018-02-12 2017-12-31 13F AMKOR TECHNOLOGY COM Put 10,200 628.57 103 586.67 n/a n/a n/a
2017-11-13 2017-09-30 13F AMKOR TECHNOLOGY COM Put 1,400 -77.78 15 -75.81 n/a n/a n/a
2017-08-11 2017-06-30 13F AMKOR TECHNOLOGY COM Put 6,300 43.18 62 21.57 n/a n/a n/a
2017-05-12 2017-03-31 13F AMKOR TECHNOLOGY COM Put 4,400 -85.38 51 -83.96 n/a n/a n/a
2017-02-10 2016-12-31 13F AMKOR TECHNOLOGY COM Put 30,100 -9.88 318 -2.15 n/a n/a n/a
2016-11-10 2016-09-30 13F AMKOR TECHNOLOGY COM Put 33,400 -33.86 325 12.07 n/a n/a n/a
2016-08-12 2016-06-30 13F AMKOR TECHNOLOGY COM Put 50,500 3.06 290 0.35 n/a n/a n/a
2016-05-13 2016-03-31 13F AMKOR TECHNOLOGY COM Put 49,000 -47.48 289 -49.03 n/a n/a n/a
2016-02-12 2015-12-31 13F AMKOR TECHNOLOGY COM Put 93,300 5.54 567 42.82 n/a n/a n/a
2015-11-13 2015-09-30 13F AMKOR TECHNOLOGY COM Put 88,400 18.18 397 -11.19 n/a n/a n/a
2015-08-13 2015-06-30 13F AMKOR TECHNOLOGY COM Put 74,800 82.00 447 23.14 n/a n/a n/a
2015-05-14 2015-03-31 13F AMKOR TECHNOLOGY COM Put 41,100 5.12 363 30.58 n/a n/a n/a
2015-02-17 2014-12-31 13F AMKOR TECHNOLOGY COM Put 39,100 187.50 278 143.86 n/a n/a n/a
2014-11-14 2014-09-30 13F AMKOR TECHNOLOGY COM Put 13,600 112.50 114 58.33 n/a n/a n/a
2014-08-14 2014-06-30 13F AMKOR TECHNOLOGY COM Put 6,400 18.52 72 94.59 n/a n/a n/a
2014-05-15 2014-03-31 13F AMKOR TECHNOLOGY COM Put 5,400 -93.16 37 -92.36 n/a n/a n/a
2014-02-14 2013-12-31 13F AMKOR TECHNOLOGY COM Put 78,900 -51.95 484 -31.25 n/a n/a n/a
2013-11-14 2013-09-30 13F AMKOR TECHNOLOGY COM Put 164,200 29.09 704 31.34 n/a n/a n/a
2013-08-14 2013-06-30 13F AMKOR TECHNOLOGY COM Put 127,200 536 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.