Octave Specialty Group, Inc.
US ˙ NYSE ˙ US0231398845

SecurityOSG / Octave Specialty Group, Inc.
InstitutionDimensional Fund Advisors Lp
Latest Disclosed Ownership2,141,047 shares
Ownership 4.60%
Dimensional Fund Advisors Lp ownership in OSG / Octave Specialty Group, Inc.

2025-10-09 - Dimensional Fund Advisors Lp has filed an SCHEDULE 13G/A form with the Securities and Exchange Commission (SEC) disclosing ownership of 2,141,047 shares of Octave Specialty Group, Inc. (US:OSG). This represents 4.6 percent ownership of the company. In their previous filing dated 2024-10-31 , Dimensional Fund Advisors Lp had reported owning 2,603,679 shares, indicating a decrease of -17.77 percent.

Institutional Ownership: 13D/G Filings

This table shows a history of the 13D/G filings made by the investor and/or investor group. Note that the share values in this table are not directly comparable to any numbers shown in the 13F table (if any).

File
Date		Effective
Date		Form Prev
Shares		 Latest
Shares		 ΔShares
(Percent)		 Ownership
(Percent)		 ΔOwnership
(Percent)
2025-10-09 2025-10-09 13G/A 2,603,679 2,141,047 -17.77 4.60 -20.69
2024-10-31 2024-10-31 13G/A 4,975,645 0 -100.00 0.00 -100.00
2024-02-09 2024-02-09 13G 2,219,789 2,603,679 17.29 5.80 18.37
2024-02-09 2024-02-09 13G 0 4,975,645 6.90
2019-02-08 2019-02-08 13G/A 2,567,046 2,219,789 -13.53 4.90 -13.58
2018-02-09 2018-02-09 13G/A 2,571,088 2,567,046 -0.16 5.67 -0.53
2017-02-09 2017-02-09 13G 2,571,088 5.70
2015-02-05 2015-02-05 13G/A 0 0.00
2014-02-10 2014-02-10 13G/A 1,749,160 5.69
2013-02-11 2013-02-11 13G/A 1,749,560 5.66
2012-02-14 2012-02-14 13G/A 1,707,188 5.60

Important Note: One of the primary uses of the 13D/G filings is to evaluate the ability of a firm to control a company (ie, the "beneficial ownership"). To that end, firms are required to report not just direct holdings in companies, but indirect holdings that they control. For investment firms, these indirect holdings can include shares in funds they manage, advisory accounts, and in the case of activist campaigns, pledged votes. Therefore, share counts listed in 13D/G filings can differ significantly than share counts listed in 13F filings.

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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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)
2026-05-07 2026-03-31 13F OCTAVE SPECIALTY GROUP COM NEW 023139884 1,310,132 -375,495 -22.28 6,092 -53.55 0.0003
2026-02-12 2025-12-31 13F OCTAVE SPECIALTY GROUP COM NEW 023139884 1,685,627 -455,420 -21.27 13,114 -26.57 0.0028
2025-11-12 2025-09-30 13F AMBAC FINL GROUP COM NEW 023139884 2,141,047 -254,690 -10.63 17,861 5.00 0.0038
2025-08-12 2025-06-30 13F AMBAC FINL GROUP COM NEW 023139884 2,395,737 -161,143 -6.30 17,010 -23.97 0.0039
2025-05-13 2025-03-31 13F AMBAC FINL GROUP COM NEW 023139884 2,556,880 -149,271 -5.52 22,372 -34.65 0.0056
2025-02-13 2024-12-31 13F AMBAC FINL GROUP COM NEW 023139884 2,706,151 -98,249 -3.50 34,232 8.89 0.0082
2024-11-07 2024-09-30 13F AMBAC FINL GROUP COM NEW 023139884 2,804,400 -148,561 -5.03 31,437 -16.96 0.0076
2024-08-09 2024-06-30 13F AMBAC FINL GROUP COM NEW 023139884 2,952,961 87,077 3.04 37,857 -15.49 0.0099
2024-05-10 2024-03-31 13F AMBAC FINL GROUP COM NEW 023139884 2,865,884 262,205 10.07 44,794 4.39 0.0121
2024-02-07 2023-12-31 13F AMBAC FINL GROUP COM NEW 023139884 2,603,679 65,733 2.59 42,908 40.19 0.0125
2023-11-09 2023-09-30 13F AMBAC FINL GROUP COM NEW 023139884 2,537,946 366,605 16.88 30,608 -1.01 0.0100
2023-08-09 2023-06-30 13F AMBAC FINL GROUP COM NEW 023139884 2,171,341 480,450 28.41 30,919 18.13 0.0099
2023-05-12 2023-03-31 13F AMBAC FINL GROUP COM NEW 023139884 1,690,891 168,422 11.06 26,174 100,569.23 0.0088
2023-02-09 2022-12-31 13F AMBAC FINL GROUP COM NEW 023139884 1,522,469 41,660 2.81 27 -99.86 0.0078
2022-11-10 2022-09-30 13F AMBAC FINL GROUP COM NEW 023139884 1,480,809 -81,148 -5.20 18,880 6.50 0.0072
2022-08-12 2022-06-30 13F AMBAC FINL GROUP COM NEW 023139884 1,561,957 -4,302 -0.27 17,727 8.83 0.0064
2022-05-13 2022-03-31 13F AMBAC FINL GROUP COM 023139884 1,566,259 91,106 6.18 16,288 -31.20 0.0050
2022-02-09 2021-12-31 13F AMBAC FINL GROUP COM 023139884 1,475,153 113,493 8.33 23,676 21.42 0.0072
2021-11-12 2021-09-30 13F AMBAC FINL GROUP COM 023139884 1,361,660 -314,925 -18.78 19,499 -25.73 0.0063
2021-08-12 2021-06-30 13F AMBAC FINL GROUP COM 023139884 1,676,585 -85,549 -4.85 26,255 -10.99 0.0083
2021-05-14 2021-03-31 13F AMBAC FINL GROUP COM 023139884 1,762,134 -86,305 -4.67 29,498 3.76 0.0098
2021-03-08 2020-12-31 13F/A-2 AMBAC FINL GROUP COM 023139884 1,848,439 -158,410 -7.89 28,429 10.93 0.0103
2021-02-11 2020-12-31 13F AMBAC FINL GROUP COM 023139884 1,848,439 -158,410 28,429 10,267.0437
2020-11-12 2020-09-30 13F AMBAC FINL GROUP COM 023139884 2,006,849 -54,682 -2.65 25,627 -13.19 0.0109
2020-08-13 2020-06-30 13F AMBAC FINL GROUP COM 023139884 2,061,531 -41,787 -1.99 29,521 13.74 0.0130
2020-05-14 2020-03-31 13F AMBAC FINL GROUP COM 023139884 2,103,318 -4,825 -0.23 25,955 -42.92 0.0135
2020-02-14 2019-12-31 13F AMBAC FINL GROUP COM 023139884 2,108,143 -12,538 -0.59 45,473 9.68 0.0166
2019-11-12 2019-09-30 13F AMBAC FINL GROUP COM 023139884 2,120,681 -17,510 -0.82 41,459 15.07 0.0161
2019-08-13 2019-06-30 13F AMBAC FINL GROUP COM 023139884 2,138,191 -6,221 -0.29 36,028 -7.28 0.0140
2019-08-12 2019-03-31 13F/A-2 AMBAC FINL GROUP COM 023139884 2,144,412 -75,377 -3.40 38,857 1.54 0.0155
2019-05-10 2019-03-31 13F AMBAC FINL GROUP COM 023139884 2,144,412 -75,377 38,857
2019-02-26 2018-12-31 13F/A-1 AMBAC FINL GROUP COM 023139884 2,219,789 -288,416 -11.50 38,269 -25.28 0.0173
2019-02-13 2018-12-31 13F AMBAC FINL GROUP COM 023139884 2,219,789 -288,416 38,269
2018-11-13 2018-09-30 13F AMBAC FINL GROUP COM 023139884 2,508,205 -32,999 -1.30 51,218 1.54 0.0195
2018-08-10 2018-06-30 13F AMBAC FINL GROUP COM 023139884 2,541,204 -25,842 -1.01 50,443 25.32 0.0201
2018-05-11 2018-03-31 13F AMBAC FINL GROUP COM 023139884 2,567,046 0 0.00 40,251 -1.88 0.0168
2018-02-12 2017-12-31 13F AMBAC FINL GROUP COM 023139884 2,567,046 0 0.00 41,021 -7.42 0.0170
2017-11-13 2017-09-30 13F AMBAC FINL GROUP COM 023139884 2,567,046 -4,042 -0.16 44,307 -0.68 0.0194
2017-08-11 2017-06-30 13F AMBAC FINL GROUP COM 023139884 2,571,088 0 0.00 44,609 -8.00 0.0206
2017-05-12 2017-03-31 13F AMBAC FINL GROUP COM 023139884 2,571,088 0 0.00 48,490 -16.18 0.0232
2017-02-09 2016-12-31 13F AMBAC FINL GROUP COM 023139884 2,571,088 146,075 6.02 57,850 29.72 0.0289
2016-11-10 2016-09-30 13F AMBAC FINL GROUP COM 023139884 2,425,013 225,815 10.27 44,596 23.20 0.0241
2016-08-09 2016-06-30 13F AMBAC FINL GROUP COM 023139884 2,199,198 562,686 34.38 36,198 928.64 0.0208
2016-05-13 2016-03-31 13F OVERSEAS SHIPHOLDING GROUP I COM 69036R400 1,636,512 -6,410 -0.39 3,519 -35.29 0.0021
2016-05-13 2016-03-31 13F OVERSEAS SHIPHOLDING GROUP I COM 69036R301 164,275 0 309 0.0002
2016-05-13 2016-03-31 13F AMBAC FINL GROUP COM 023139884 1,802,712 208,770 28,483 0.0170
2016-02-10 2015-12-31 13F OVERSEAS SHIPHOLDING GROUP I COM 69036R400 1,642,922 -200 -0.01 5,438 -2.37 0.0034
2016-02-10 2015-12-31 13F OVERSEAS SHIPHOLDING GROUP I COM 69036R301 164,275 -1,478,847 465 0.0003
2016-02-10 2015-12-31 13F AMBAC FINL GROUP COM 023139884 1,593,942 14,163 22,459 0.0140
2015-11-13 2015-09-30 13F OVERSEAS SHIPHOLDING GROUP I COM 69036R400 1,643,122 0 0.00 5,570 -3.15 0.0037
2015-11-13 2015-09-30 13F AMBAC FINL GROUP COM 023139884 1,579,779 19,788 22,860 0.0150
2015-08-14 2015-06-30 13F OVERSEAS SHIPHOLDING GROUP I COM 69036R400 1,643,122 0 0.00 5,751 -14.64 0.0035
2015-08-14 2015-06-30 13F AMBAC FINL GROUP COM 023139884 1,559,991 203,678 25,964 0.0159
2015-05-14 2015-03-31 13F OVERSEAS SHIPHOLDING GROUP I COM 69036R400 1,643,122 -7,220 -0.44 6,737 -25.78 0.0043
2015-05-14 2015-03-31 13F AMBAC FINL GROUP COM 023139884 1,356,313 243,812 32,823 0.0207
2015-02-06 2014-12-31 13F OVERSEAS SHIPHOLDING GROUP I COM 69036R400 1,650,342 632,224 62.10 9,077 -59.66 0.0060
2015-02-06 2014-12-31 13F AMBAC FINL GROUP COM 023139884 1,112,501 94,383 27,257 0.0179
2014-11-13 2014-09-30 13F AMBAC FINL GROUP COM 023139884 1,018,118 204,744 25.17 22,501 1.30 0.0159
2014-08-08 2014-06-30 13F AMBAC FINL GROUP COM 023139884 813,374 444,363 120.42 22,213 93.98 0.0154
2014-05-14 2014-03-31 13F AMBAC FINL GROUP COM 023139884 369,011 334,757 977.28 11,451 1,261.59 0.0086
2014-02-12 2013-12-31 13F AMBAC FINL GROUP COM 023139884 34,254 34,254 841 0.0007
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.