Arch Capital Group Ltd. (ACGL)

The full register, from 13F filings

The Register tab above is hand research: a dozen holders, each traced to the filing it came from. This asks the same question of the whole market for the quarter ended 31-mar-2026, where 899 managers reported a position. Broad where the research is deep, and shallow in the ways a 13F always is.

Built from 13F filings, which report US listed, long, US custodied positions only. A register from this source is a floor rather than a level: a holder's true position can be far larger, as BlackRock's ASML stake shows at 1.28m shares in a 13F against 26.3m in its 13G/A. Holdings held through derivatives, outside US custody, or below a manager's reporting obligation do not appear. Where a holder is marked as a family, its total sums several separate filing entities and describes something no single filing describes; the constituent entities and their share counts are listed so the total can be checked. That roll-up can legitimately exceed the family's own Schedule 13G, because a 13G is filed by one legal entity: Vanguard reports Alphabet through ten advisory entities, and The Vanguard Group Inc itself reported zero after its January 2026 disaggregation.

What a reader needs to know to read these numbers

• company.shares_outstanding (341,229,126) is dei:EntityCommonStockSharesOutstanding from the cover page of the Q2 2026 10-Q (filed 4 Aug 2026, period 30 Jun 2026), as of 30 Jul 2026. This tag is defined as shares issued and outstanding, i.e. net of treasury shares; every register row's pct_denominator uses this same figure.
• Arch Capital has two series of preferred stock, each listed as depositary shares on Nasdaq: Series F (5.45%, ticker ACGLO) and Series G (4.55%, ticker ACGLN), per the 10-Q cover page. shares_outstanding is common shares only. Every register row above was checked against CUSIP G0450A105 (the common CUSIP); none of the 13F filers checked reported ACGL under a different (preferred) CUSIP, so no preferred or depositary position is counted in any register row.
• Self-gate, computed from this file exactly as the chart computes it: 13 register rows, no rolls_up_into/is_aggregate linkages (no member double-counting risk), total shares 175,358,814, which is 51.39% of shares_outstanding (341,229,126). This is within the brief's 15-55% bound but above the 'roughly 25-45%' typical range; the excess comes from ACGL being unusually concentrated among a handful of large active and index managers (Vanguard 11.83%, BlackRock 8.86%, Artisan Partners 6.33%, State Street 4.76%, BAMCO 4.65% alone sum to over 36%) rather than from any counting error found during review.
• Vanguard: parent Vanguard Group Inc (CIK 0000102909) filed Form 13F-NT (no holdings) for Q2 2026, so all 8 successor entities were summed (never substituted), matching the PNC-style rule. Entity list enumerated from this project's own data/registers/ACGL.json (a 31 Mar 2026 snapshot, used only to identify WHICH entities to check, per the brief); every share figure was refetched from each entity's own fresh Q2 2026 13F-HR.
• Capital Group and T. Rowe Price were swept per the brief's instructions even though this project's own ACGL.json snapshot did not list either family. Only Capital International Investors (of Capital Group's three standard registrants) and T. Rowe Price Associates (of its two registrants) hold ACGL; the other three checked entities hold zero. Both are small (0.24% and 0.15% of the company respectively) but are included as verified, sourced, nonzero positions rather than omitted.
• T. Rowe Price Associates files its 13F value field in THOUSANDS. The raw filing showed $50,842 for 523,807 shares; converted to $50,842,000, giving an implied price of $97.06/share, consistent with every other Q2 2026 13F filer checked (all cluster around $97.06/share, ACGL's approximate price at 30 Jun 2026).
• The 2026 DEF 14A's 5%-holder table is stale, sourced to older Schedule 13G/A filings (Vanguard as of 29 Dec 2023, BlackRock as of 30 Sep 2024, Artisan Partners Holdings LP undated but pre-2026). Fresh Q2 2026 13F-HR figures are used as primary throughout, per the brief; the proxy's Artisan Partners Holdings LP figure (24,894,249 sh, 7.0%) is a related but distinct filer from the Artisan Partners Limited Partnership CIK used in the register row here (21,595,895 sh), and the two should not be summed.
• Baron Capital Group, Inc. and Ronald Baron were a >5% holder as recently as the prior proxy cycle but the 2026 DEF 14A states Baron 'no longer beneficially owned more than 5% of the outstanding common shares of Arch Capital as of December 31, 2025.' Treated as an exited position: a note, not a row.
• Arch Capital itself files a 13F-HR (CIK 0000947484, most recent for Q2 2026, filed 4 Aug 2026) as an institutional investment manager. It lists only 4 positions, all fixed-income ETF/CLO fund holdings (Janus Detroit Street Trust AAA CLO ETF, iShares 0-5 Year High Yield Corporate Bond ETF, iShares 1-5 Year Investment Grade Corporate Bond ETF, iShares iBoxx High Yield Corporate Bond ETF), totaling $290,954,000. These are part of Arch's fixed-maturity/investment portfolio and are excluded from holdings per the brief's scope (treasury-style holdings, not strategic equity); no other listed equity positions were found via this route.
• Exhibit 21 of the FY2025 10-K lists only wholly owned subsidiaries with no ownership-percentage column, and does not include Coface, Greysbridge or Premia (consistent with them being non-wholly-owned equity-method investees rather than subsidiaries). This is a genuine negative finding, not a gap: Exhibit 21 gave no percentage information usable for sizing any holding here.
• Searched the FY2025 10-K and Q2 2026 10-Q for 'unconsolidated', 'non-marketable equity', 'investments in related parties' and 'joint venture': no hits beyond the Coface/Greysbridge/Premia equity-method investees already covered. 'Watford' does not occur anywhere in the Q2 2026 10-Q; the entity is referred to only as Somers Group Holdings Ltd. / Somers Re Ltd. throughout current filings.
• During 2024 Arch separately acquired Watford Insurance Company (a specific licensed insurer) directly from Somers for $35 million; this became a wholly owned Arch subsidiary and is excluded from holdings as a wholly owned operating subsidiary, per the brief. Arch also separately holds $35 million in aggregate principal amount of Somers 6.5% senior notes due 2029, which is a debt instrument, not equity, and is excluded.
• market_cap_usd (33.61bn) and market_cap_as_of (2026-08-18) come from stockanalysis.com, an aggregator, since no SEC filing states a market capitalization directly; this aggregator also reported 339.82 million shares outstanding as of the same date, close to but not identical to the SEC-filed 341,229,126 as of 30 Jul 2026 used as company.shares_outstanding, consistent with routine buybacks/drift rather than an error.