Rambus Inc.
US ˙ NasdaqGS ˙ US7509171069

SecurityRMBS / Rambus Inc.
InstitutionCitigroup Inc
Latest Disclosed Ownership1,007,548 shares
Latest Disclosed Value $ 86,679,354
Citigroup Inc ownership in RMBS / Rambus Inc.

On May 11, 2026 - Citigroup Inc filed a 13F-HR form disclosing ownership of 1,007,548 shares of Rambus Inc. (US:RMBS) valued at $86,679,354 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 502,540 shares of Rambus Inc.. This represents a change in shares of 100.49% during the quarter. The current value of the position is $171,948,142 USD.

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

RMBS / Rambus 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 RAMBUS INC DEL COM 750917106 1,007,548 505,008 100.49 86,679 87.71 0.0370
2026-02-13 2025-12-31 13F RAMBUS INC DEL COM 750917106 502,540 132,199 35.70 46,178 19.67 0.0204
2025-11-10 2025-09-30 13F RAMBUS INC DEL COM 750917106 370,341 220,207 146.67 38,590 301.51 0.0172
2025-08-11 2025-06-30 13F RAMBUS INC DEL COM 750917106 150,134 38,180 34.10 9,612 65.82 0.0047
2025-05-12 2025-03-31 13F RAMBUS INC DEL COM 750917106 111,954 -5,246 -4.48 5,796 -6.44 0.0030
2025-02-12 2024-12-31 13F RAMBUS INC DEL COM 750917106 117,200 4,285 3.79 6,195 29.96 0.0037
2024-11-12 2024-09-30 13F RAMBUS INC DEL COM 750917106 112,915 -564,655 -83.34 4,767 -88.03 0.0028
2024-08-12 2024-06-30 13F RAMBUS INC DEL COM 750917106 677,570 144,654 27.14 39,814 20.87 0.0255
2024-05-10 2024-03-31 13F RAMBUS INC DEL COM 750917106 532,916 328,341 160.50 32,940 135.92 0.0216
2024-02-09 2023-12-31 13F RAMBUS INC DEL COM 750917106 204,575 -65,834 -24.35 13,962 -7.45 0.0098
2023-12-06 2023-09-30 13F/A-1 RAMBUS INC DEL COM 750917106 270,409 152,179 128.71 15,086 98.87 0.0113
2023-11-09 2023-09-30 13F RAMBUS INC DEL COM 750917106 270,409 152,179 15,086 0.0045
2023-08-10 2023-06-30 13F RAMBUS INC DEL COM 750917106 118,230 44,966 61.38 7,587 102.02 0.0050
2023-05-11 2023-03-31 13F RAMBUS INC DEL COM 750917106 73,264 -15,323 -17.30 3,756 18.34 0.0026
2023-02-09 2022-12-31 13F RAMBUS INC DEL COM 750917106 88,587 -10,614 -10.70 3,173 25.81 0.0025
2022-11-10 2022-09-30 13F RAMBUS INC DEL COM 750917106 99,201 20,040 25.32 2,522 48.18 0.0018
2022-08-10 2022-06-30 13F RAMBUS INC DEL COM 750917106 79,161 -48,123 -37.81 1,702 -58.07 0.0013
2022-05-12 2022-03-31 13F RAMBUS INC DEL COM 750917106 127,284 -2,738 -2.11 4,059 6.23 0.0025
2022-02-10 2021-12-31 13F RAMBUS INC DEL COM 750917106 130,022 40,007 44.44 3,821 91.15 0.0020
2021-11-10 2021-09-30 13F RAMBUS INC DEL COM 750917106 90,015 -19,068 -17.48 1,999 -22.70 0.0012
2021-08-10 2021-06-30 13F RAMBUS INC DEL COM 750917106 109,083 57,776 112.61 2,586 159.38 0.0016
2021-05-13 2021-03-31 13F RAMBUS INC DEL COM 750917106 51,307 -6,969 -11.96 997 -1.97 0.0006
2021-02-11 2020-12-31 13F RAMBUS INC DEL COM 750917106 58,276 18,060 44.91 1,017 84.91 0.0006
2020-11-12 2020-09-30 13F RAMBUS INC DEL COM 750917106 40,216 -50,352 -55.60 550 -60.03 0.0004
2020-08-12 2020-06-30 13F RAMBUS INC DEL COM 750917106 90,568 23,662 35.37 1,376 85.20 0.0011
2020-05-12 2020-03-31 13F RAMBUS INC DEL COM 750917106 66,906 13,589 25.49 743 1.23 0.0007
2020-02-12 2019-12-31 13F RAMBUS INC DEL COM 750917106 53,317 -30,054 -36.05 734 -32.97 0.0005
2019-11-08 2019-09-30 13F RAMBUS INC DEL COM 750917106 83,371 29,939 56.03 1,095 70.30 0.0009
2019-08-12 2019-06-30 13F RAMBUS INC DEL COM 750917106 53,432 -25,285 -32.12 643 -21.78 0.0005
2019-05-13 2019-03-31 13F RAMBUS INC DEL COM 750917106 78,717 5,433 7.41 822 46.26 0.0008
2019-02-12 2018-12-31 13F RAMBUS INC DEL COM 750917106 73,284 35,388 93.38 562 36.08 0.0006
2018-11-13 2018-09-30 13F RAMBUS INC DEL COM 750917106 37,896 -15,353 -28.83 413 -38.08 0.0004
2018-08-10 2018-06-30 13F RAMBUS INC DEL COM 750917106 53,249 27,018 103.00 667 89.49 0.0006
2018-05-11 2018-03-31 13F RAMBUS INC DEL COM 750917106 26,231 -92,372 -77.88 352 -79.12 0.0003
2018-02-12 2017-12-31 13F RAMBUS INC DEL COM 750917106 118,603 -19,217 -13.94 1,686 -8.37 0.0014
2017-11-13 2017-09-30 13F RAMBUS INC DEL COM 750917106 137,820 -77,989 -36.14 1,840 -25.39 0.0015
2017-08-11 2017-06-30 13F RAMBUS INC DEL COM 750917106 215,809 28,451 15.19 2,466 0.16 0.0022
2017-05-12 2017-03-31 13F RAMBUS INC DEL COM 750917106 187,358 -30,397 -13.96 2,462 -17.91 0.0022
2017-02-10 2016-12-31 13F RAMBUS INC DEL COM 750917106 217,755 58,589 36.81 2,999 50.70 0.0027
2016-11-10 2016-09-30 13F RAMBUS INC DEL COM 750917106 159,166 44,821 39.20 1,990 43.99 0.0019
2016-08-12 2016-06-30 13F RAMBUS INC DEL COM 750917106 114,345 -53,908 -32.04 1,382 -40.28 0.0014
2016-05-13 2016-03-31 13F RAMBUS INC DEL COM 750917106 168,253 124,116 281.21 2,314 352.84 0.0026
2016-02-12 2015-12-31 13F RAMBUS INC DEL COM 750917106 44,137 -47,673 -51.93 511 -52.86 0.0005
2015-11-13 2015-09-30 13F RAMBUS INC DEL COM 750917106 91,810 -72,269 -44.05 1,084 -54.42 0.0010
2015-08-13 2015-06-30 13F RAMBUS INC DEL COM 750917106 164,079 -77,508 -32.08 2,378 -21.70 0.0021
2015-05-14 2015-03-31 13F RAMBUS INC DEL COM 750917106 241,587 69,230 40.17 3,037 58.92 0.0029
2015-02-17 2014-12-31 13F RAMBUS INC DEL COM 750917106 172,357 12,845 8.05 1,911 -4.02 0.0017
2014-11-14 2014-09-30 13F RAMBUS INC DEL COM 750917106 159,512 24,788 18.40 1,991 3.32 0.0017
2014-08-14 2014-06-30 13F RAMBUS INC DEL COM 750917106 134,724 28,788 27.17 1,927 69.33 0.0018
2014-05-15 2014-03-31 13F RAMBUS INC DEL COM 750917106 105,936 -76,866 -42.05 1,138 -34.30 0.0012
2014-02-14 2013-12-31 13F RAMBUS INC DEL COM 750917106 182,802 116,178 174.38 1,732 176.24 0.0016
2013-11-14 2013-09-30 13F RAMBUS INC DEL COM 750917106 66,624 -15,180 -18.56 627 -10.68 0.0006
2013-08-14 2013-06-30 13F RAMBUS INC DEL COM 750917106 81,804 81,804 702 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
(%)
2021-05-13 2021-03-31 13F RAMBUS INC DEL COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2021-02-11 2020-12-31 13F RAMBUS INC DEL COM Call 20,600 -64.97 360 -55.28 n/a n/a n/a
2020-11-12 2020-09-30 13F RAMBUS INC DEL COM Call 58,800 -0.68 805 -10.56 n/a n/a n/a
2020-08-12 2020-06-30 13F RAMBUS INC DEL COM Call 59,200 42.31 900 94.81 n/a n/a n/a
2020-05-12 2020-03-31 13F RAMBUS INC DEL COM Call 41,600 -24.50 462 -39.13 n/a n/a n/a
2020-02-12 2019-12-31 13F RAMBUS INC DEL COM Call 55,100 -39.72 759 -36.75 n/a n/a n/a
2019-11-08 2019-09-30 13F RAMBUS INC DEL COM Call 91,400 20.74 1,200 31.72 n/a n/a n/a
2019-08-12 2019-06-30 13F RAMBUS INC DEL COM Call 75,700 107.97 911 139.74 n/a n/a n/a
2019-05-13 2019-03-31 13F RAMBUS INC DEL COM Call 36,400 -1.36 380 34.28 n/a n/a n/a
2019-02-12 2018-12-31 13F RAMBUS INC DEL COM Call 36,900 13.54 283 -20.28 n/a n/a n/a
2018-11-13 2018-09-30 13F RAMBUS INC DEL COM Call 32,500 -25.29 355 -34.86 n/a n/a n/a
2018-08-10 2018-06-30 13F RAMBUS INC DEL COM Call 43,500 30.63 545 21.92 n/a n/a n/a
2018-05-11 2018-03-31 13F RAMBUS INC DEL COM Call 33,300 -46.81 447 -49.78 n/a n/a n/a
2018-02-12 2017-12-31 13F RAMBUS INC DEL COM Call 62,600 -24.03 890 -19.09 n/a n/a n/a
2017-11-13 2017-09-30 13F RAMBUS INC DEL COM Call 82,400 -14.96 1,100 -0.72 n/a n/a n/a
2017-08-11 2017-06-30 13F RAMBUS INC DEL COM Call 96,900 -18.71 1,108 -29.25 n/a n/a n/a
2017-05-12 2017-03-31 13F RAMBUS INC DEL COM Call 119,200 -2.38 1,566 -6.84 n/a n/a n/a
2017-02-10 2016-12-31 13F RAMBUS INC DEL COM Call 122,100 2.78 1,681 13.20 n/a n/a n/a
2016-11-10 2016-09-30 13F RAMBUS INC DEL COM Call 118,800 -4.35 1,485 -1.00 n/a n/a n/a
2016-08-12 2016-06-30 13F RAMBUS INC DEL COM Call 124,200 35.44 1,500 18.95 n/a n/a n/a
2016-05-13 2016-03-31 13F RAMBUS INC DEL COM Call 91,700 -71.37 1,261 -66.03 n/a n/a n/a
2016-02-12 2015-12-31 13F RAMBUS INC DEL COM Call 320,300 415.78 3,712 406.41 n/a n/a n/a
2015-11-13 2015-09-30 13F RAMBUS INC DEL COM Call 62,100 -13.63 733 -29.65 n/a n/a n/a
2015-08-13 2015-06-30 13F RAMBUS INC DEL COM Call 71,900 28.85 1,042 48.43 n/a n/a n/a
2015-05-14 2015-03-31 13F RAMBUS INC DEL COM Call 55,800 -63.58 702 -58.68 n/a n/a n/a
2015-02-17 2014-12-31 13F RAMBUS INC DEL COM Call 153,200 -23.25 1,699 -31.79 n/a n/a n/a
2014-11-14 2014-09-30 13F RAMBUS INC DEL COM Call 199,600 24.36 2,491 8.54 n/a n/a n/a
2014-08-14 2014-06-30 13F RAMBUS INC DEL COM Call 160,500 31.67 2,295 75.19 n/a n/a n/a
2014-05-15 2014-03-31 13F RAMBUS INC DEL COM Call 121,900 13.08 1,310 28.31 n/a n/a n/a
2014-02-14 2013-12-31 13F RAMBUS INC DEL COM Call 107,800 -29.91 1,021 -29.39 n/a n/a n/a
2013-11-14 2013-09-30 13F RAMBUS INC DEL COM Call 153,800 46.48 1,446 60.31 n/a n/a n/a
2013-08-14 2013-06-30 13F RAMBUS INC DEL COM Call 105,000 902 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
(%)
2021-05-13 2021-03-31 13F RAMBUS INC DEL COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2021-02-11 2020-12-31 13F RAMBUS INC DEL COM Put 7,100 -6.58 124 19.23 n/a n/a n/a
2020-11-12 2020-09-30 13F RAMBUS INC DEL COM Put 7,600 15.15 104 4.00 n/a n/a n/a
2020-08-12 2020-06-30 13F RAMBUS INC DEL COM Put 6,600 15.79 100 58.73 n/a n/a n/a
2020-05-12 2020-03-31 13F RAMBUS INC DEL COM Put 5,700 -69.84 63 -75.77 n/a n/a n/a
2020-02-12 2019-12-31 13F RAMBUS INC DEL COM Put 18,900 9.25 260 14.54 n/a n/a n/a
2019-11-08 2019-09-30 13F RAMBUS INC DEL COM Put 17,300 -11.73 227 -3.81 n/a n/a n/a
2019-08-12 2019-06-30 13F RAMBUS INC DEL COM Put 19,600 136.14 236 171.26 n/a n/a n/a
2019-05-13 2019-03-31 13F RAMBUS INC DEL COM Put 8,300 -4.60 87 29.85 n/a n/a n/a
2019-02-12 2018-12-31 13F RAMBUS INC DEL COM Put 8,700 -16.35 67 -40.71 n/a n/a n/a
2018-11-13 2018-09-30 13F RAMBUS INC DEL COM Put 10,400 -68.10 113 -72.37 n/a n/a n/a
2018-08-10 2018-06-30 13F RAMBUS INC DEL COM Put 32,600 0.00 409 -6.62 n/a n/a n/a
2018-05-11 2018-03-31 13F RAMBUS INC DEL COM Put 32,600 -60.96 438 -63.10 n/a n/a n/a
2018-02-12 2017-12-31 13F RAMBUS INC DEL COM Put 83,500 -6.29 1,187 -0.17 n/a n/a n/a
2017-11-13 2017-09-30 13F RAMBUS INC DEL COM Put 89,100 -3.05 1,189 13.24 n/a n/a n/a
2017-08-11 2017-06-30 13F RAMBUS INC DEL COM Put 91,900 3.03 1,050 -10.41 n/a n/a n/a
2017-05-12 2017-03-31 13F RAMBUS INC DEL COM Put 89,200 -17.10 1,172 -20.92 n/a n/a n/a
2017-02-10 2016-12-31 13F RAMBUS INC DEL COM Put 107,600 17.98 1,482 30.00 n/a n/a n/a
2016-11-10 2016-09-30 13F RAMBUS INC DEL COM Put 91,200 -3.90 1,140 -0.52 n/a n/a n/a
2016-08-12 2016-06-30 13F RAMBUS INC DEL COM Put 94,900 -20.52 1,146 -30.21 n/a n/a n/a
2016-05-13 2016-03-31 13F RAMBUS INC DEL COM Put 119,400 -34.18 1,642 -21.88 n/a n/a n/a
2016-02-12 2015-12-31 13F RAMBUS INC DEL COM Put 181,400 50.04 2,102 47.30 n/a n/a n/a
2015-11-13 2015-09-30 13F RAMBUS INC DEL COM Put 120,900 4.04 1,427 -15.26 n/a n/a n/a
2015-08-13 2015-06-30 13F RAMBUS INC DEL COM Put 116,200 -8.72 1,684 5.18 n/a n/a n/a
2015-05-14 2015-03-31 13F RAMBUS INC DEL COM Put 127,300 -21.27 1,601 -10.71 n/a n/a n/a
2015-02-17 2014-12-31 13F RAMBUS INC DEL COM Put 161,700 -8.75 1,793 -18.91 n/a n/a n/a
2014-11-14 2014-09-30 13F RAMBUS INC DEL COM Put 177,200 13.81 2,211 -0.72 n/a n/a n/a
2014-08-14 2014-06-30 13F RAMBUS INC DEL COM Put 155,700 196.01 2,227 294.16 n/a n/a n/a
2014-05-15 2014-03-31 13F RAMBUS INC DEL COM Put 52,600 -43.74 565 -36.16 n/a n/a n/a
2014-02-14 2013-12-31 13F RAMBUS INC DEL COM Put 93,500 9.74 885 10.49 n/a n/a n/a
2013-11-14 2013-09-30 13F RAMBUS INC DEL COM Put 85,200 -25.33 801 -18.27 n/a n/a n/a
2013-08-14 2013-06-30 13F RAMBUS INC DEL COM Put 114,100 980 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.