Five of 147: Avoro Holds 76.9% of the Tracked Arrowhead Stake, and the Verified Cohort Grew 3.3% in a Quarter When the Price Rose 30.0%

GetCoattail Research — The Filing Tape #121. Arrowhead Pharmaceuticals surfaced on a trending-stocks screen this week listed as a Strong Buy with four Buy ratings and no Hold or Sell, and the filings describe a concentrated tracked register that grew into a rising price: 5 of the 147 superinvestors held the common stock at June 30, 2026, totalling 14,769,005 shares, with the four continuing holders verified against the first quarter for a combined increase of 3.3%. Insiders have recorded no purchase in any window of the parsed record, no congressional aggregate carries a row for the name, and short interest stands at 6.56% of shares outstanding, down 21.8% from a year ago.

The Hype

Arrowhead's attention this week is a screen story. The stock appeared on TipRanks' Trending Stocks by Analyst screener — SCHW, SMTC and BAC topped the page's order, followed by names already covered in this series, among them RKLB, JBHT, USB, BNY, MSFT, VSTM, BLK, CRWV, PGR, META and UNH — and Arrowhead followed them, listed as a Strong Buy with a price target of $109.00 (94.99% upside as printed), 4 Buy, 0 Hold and 0 Sell ratings, a market value of $7.90B as printed, in Healthcare, dated October 15, 2026. TipRanks Our price file shows the path behind the screen: the stock rose 30.0% in the second quarter, from $62.70 on March 31 to $81.51 on June 30, and closed at $64.19 on October 2 — down 21.2% from the June 30 close and 28.4% below the 252-session closing high of $89.59 (August 4, 2026). That is what this series checks against the filings.

The Tape

For Arrowhead Pharmaceuticals — the one hundred and twenty-first Filing Tape audit — the tape shows a five-manager common-stock cohort dominated by one holder and growing a verified 3.3% into a rising price, a full market adding filers and shares faster, an insider record with no purchase in any window, no congressional row, a 5% register whose only activist-family filer has printed zero, and a borrow below its 2025 peak.

Lens 1 — the superinvestors: five common-stock holders, one of them 76.9% of the stake, growing 3.3% into the rise. We track 149 managers whose 13F portfolios we collect from SEC EDGAR — 147 are in the collection (144 at a June 30 period-end, 3 early filers at September 30, none of them holding this name) — and the June 30, 2026 register for the common stock, on CUSIP 04280A100, is 5 distinct managers holding 14,769,005 shares worth $1,203,821,597, long only, with no option rows: 1 labelled INCREASED, 2 UNCHANGED, 1 DECREASED and 1 NEW. Avoro Capital Advisors is the largest: 11,355,555 shares worth $925,591,288 — 76.9% of the tracked stake — at an 8.31% portfolio weight, labelled INCREASED at +6.1%. Baker Bros. Advisors is second at 1,992,783 shares (13.5%), labelled UNCHANGED, so the top two hold 13,348,338 shares, 90.4% of the cohort. Deerfield Management holds 1,389,055 common shares, labelled DECREASED at -11.7%; Edgewood Management holds 25,000 shares, UNCHANGED; and Polen Capital Management holds 6,612 shares, labelled NEW. Two further tracked rows sit on a different CUSIP for the issuer's convertible debt and are not common shares, so they are counted separately in the methodology, not here. The increase verifies row by row under two independent register methods that agree on every holder (see methodology): the four continuing holders held 14,291,079 shares at March 31 and 14,762,393 at June 30 (+471,314 shares, +3.3%), with no unverified holder. One tracked manager, RTW Investments, held 585,682 shares at March 31 and no longer appears — counting that exit and the new holder, the full register moved from 14,876,761 shares to 14,769,005 (-0.7%). Every common row implies $81.51, the June 30 close. 13F figures are as of June 30, 2026, published up to 45 days later.

Lens 2 — institutions: 74 more filers and 12.01% more shares, growing faster than the tracked cohort. At June 30, 2026, 505 institutions reported positions, up 74 from 431 at March 31 (+17.17%); 498 are long. Reported shares rose 12.01%, from 106,384,230 to 119,163,036 (+12,778,806 shares), and reported value rose 45.11% to $9,711,116,012, labelled "reported" because the aggregate includes option rows (see methodology). Flow counts agree: 480 entered, 406 exited, a net of +74, and the single by-CUSIP row matches the by-ticker row on every field. The reported value implies $81.49 per share against a June 30 close of $81.51 (-0.02%, from the unrounded implied price).

Lens 3 — insiders: no purchase in any window, against 88 sales. The parsed Form 4 record holds 44 filings through October 2, 2026, and it contains no purchase transaction: 0 purchases, 0 buyers and 0 officer purchases in the 90-day window, the one-year window and the full record. The last 90 days hold 0 purchases and 2 sales: 13,600 shares for $1,186,600.00, by 2 sellers, none of them officer sale transactions, across 2 filings. The one-year window holds 65 sales (580,501 shares, $38,044,096.32, 10 sellers, 50 of them officer sale transactions) across 31 filings, and the full record holds 88 sales (1,240,607 shares, $49,169,314.58, 11 sellers, 72 of them officer sale transactions). The sales imply $87.25 per share in the 90-day window, $65.54 over one year and $39.63 over the full record, each inside that window's close range on our price file ($64.19 to $89.59, $35.41 to $89.59 and the full-period range) — so the dollar totals are cited for every window. The site's insider aggregate matches the full parse's 90-day window exactly (methodology).

Lens 4 — Congress: no row in any aggregate. The combined record (as of October 3, 2026) carries no row for this name. The House aggregate (as of October 3, 2026) carries no row, and the Senate aggregate (as of October 1, 2026) carries no row — no congressional transaction for this name sits in any archive.

Lens 5 — the 5% register: 18 filings, an activist-family stake that printed zero, and a 15.0% maximum. Our full parse holds 18 SC 13D/G filings matching the site aggregate — 2 in the SC 13D family (1 SC 13D and 1 SC 13D/A), 6 SC 13G and 10 SC 13G/A; 11 of them amendments, 11 reporter names. The register maximum is 15.0%: BlackRock, Inc. printed 20,323,221 shares at 15.0% as of December 31, 2025 (filed January 21, 2026, SC 13G/A); its later prints are 12.2% as of March 31, 2026 and 10.1% as of June 30, 2026. The only SC 13D family filer, Sarepta Therapeutics, Inc. with Sarepta Therapeutics Investments, Inc., printed 11,926,301 shares at 9.5% as of February 7, 2025 — and its amendment prints 0 shares at 0.0% as of August 13, 2025. The latest filing prints Avoro Capital Advisors LLC and Behzad Aghazadeh at 13,823,383 shares each (9.64%) as of June 30, 2026 (filed August 14, 2026) — two reporter rows on the same stake, not two stakes. The 239,610,029.5-share total counts reporter rows across dates, not distinct stakes.

Lens 6 — short interest: a mid-sized borrow, down from its peak and below a year ago. The latest FINRA settlement, September 15, 2026, records 9,272,290 shares sold short — 6.56% of the 141,254,467 shares outstanding — at 5.15 days to cover, down 1.64% from the prior settlement (9,426,449 on August 31, 2026). Against the June 30, 2026 settlement (8,430,780) the latest is up 10.0%, and against the year-ago settlement (11,862,693 on September 15, 2025) it is down 21.8%. The series maximum across 137 settlements is 13,527,313 on April 30, 2025, so the latest sits 31.5% below that peak. The recent path runs 8,430,780 (June 30), 9,635,297 (July 15), 9,656,078 (July 31), 9,207,426 (August 14), 9,426,449 (August 31) and 9,272,290 (September 15). No step in the series reaches 2 times in either direction (methodology); the series is published as collected.

The Gap

The narrative arriving this week is an analyst-consensus story: a Strong Buy trending listing, 4 Buy ratings against no Hold or Sell, a printed target far above the last close, on a stock that rose 30.0% in the second quarter on our price file — and then gave back 21.2% of that level by October 2. The filings give the trend a real but narrow base. The broad market added exposure — 74 more filers and 12.01% more shares — and the tracked cohort grew too, but the growth is one name: Avoro, at 76.9% of the tracked stake, added 6.1%, while Deerfield trimmed 11.7%, two holders sat unchanged, and RTW's March position disappeared. The insider record runs one way: no purchase in any window of a 44-filing record, only sales, and no congressional aggregate carries the name. The borrow is not building against the story — at 6.56% of the share count it is down 21.8% year over year — and the register's only activist-family stake, Sarepta's, has already printed zero. One plausible reading is that the trending case rests on the analyst screen and the second quarter's price run, while the June tape shows broad and tracked registers both adding, insider confirmation absent, and the clearest tracked conviction concentrated in a single holder — breadth in the aggregate, concentration in the tracked names.

What Would Change the Picture

Nothing above is a recommendation. These filings would change it:

• 1. The 2026Q3 13F season (filing window closing mid-November 2026). The four continuing June holders verify, so the cohort's +3.3% is a clean baseline. Whether Avoro Capital Advisors' 11,355,555-share stake grows again after a quarter in which the price fell 21.2% from its June 30 close decides whether the June increase reads as conviction being added to, or a position the third quarter reverses.
• 2. A first insider purchase. The parsed record holds 0 purchases in 44 filings, in every window. A first purchase transaction would break the sales-only record.
• 3. A first congressional row. The combined, House and Senate aggregates all carry no row for this name. A first recorded transaction in either chamber would open this lens.
• 4. A new SC 13D, or a 5% print above 15.0%. The register's only activist-family filer, Sarepta, printed 0.0% in its amendment, and its maximum, BlackRock's 15.0% print as of December 31, 2025, has since been followed by lower prints. A new activist-family filing, or a new filing moving the maximum, would change this lens.
• 5. Short interest through the series peak, or back below the June 2026 level. The borrow stands at 9,272,290 shares, down 1.64% on the settlement and down 21.8% year over year, at 6.56% of shares outstanding. A reading at or above 13,527,313 would set a new series high; a fall back below 8,430,780 would unwind the post-June rise.

Related reading: Four of 147: Bill Nygren - Oakmark Funds Holds 67.3% of the Tracked Targa Resources Stake, and the Cohort Cut 6.4% in a Quarter When the Price Rose 6.9% — Filing Tape #120; Four of 147: RTW Holds 43.2% of the Tracked Verastem Stake, and the Cohort Grew 16.3% in a Quarter When the Price Fell 27.9% — Filing Tape #119. Arrowhead Pharmaceuticals' own page: Arrowhead Pharmaceuticals (ARWR) on GetCoattail.

Methodology and data notes

• As-of & limits: The lenses rest on different clocks, none live: 13F is a June 30, 2026 snapshot published up to 45 days later; Form 4 runs through October 2, 2026; Congress aggregates run through October 3, 2026 (Senate through October 1, 2026); 13D/G through August 14, 2026; short interest through September 15, 2026; the price file ends October 2, 2026. Six limits are specific to this audit. First, the roster expanded before the recent audits — from 85 managers (83 filing) to 149 (147 filing) — so "of 147" counts are not comparable to earlier pieces' "of 83" figures. Second, the tracked collection mixes period-ends in general, but for this name all five common-stock holders sit on June 30, 2026 period-ends and none of the three September 30 early filers holds it, so every superinvestor figure here is a single-date figure. Third, this issuer carries two CUSIPs in the tracked collection: the common stock (04280A100) and a convertible-debt CUSIP (04280AAC4) whose rows report principal amounts, not shares — every share count in this audit is on the common CUSIP only, and the debt rows are detailed in the superinvestor note below. Fourth, the full-market reported value rose 45.11% while reported shares rose 12.01%; the value implies $81.49 per share against the $81.51 June 30 close (-0.02%, computed from the unrounded implied price), and filer and share counts are headlined. Fifth, the short-interest series carries one FINRA revision-flag row, in 2021, detailed in the short-interest note below; it is not connected to any step in the series, and the series is published as collected. Sixth, the TipRanks screener listing (dated October 15, 2026 on the page) postdates the 13F snapshot and the short-interest series; the listing is known to this audit only from outside coverage, not from our own files, and none of its price figures are cited here beyond the listing's own printed target and market value, which are reported as screen content in The Hype; every other price figure here is from our own price file.
• Superinvestor lens: 147 managers in the collection (of a 149-manager roster; 144 at a June 30, 2026 period-end and 3 early filers at September 30, 2026, none of them holding this name) collected directly from SEC EDGAR Form 13F (managers_13f collection, regenerated October 15, 2026 for the expanded roster); Arrowhead positions are counted on the common-stock CUSIP 04280A100, long rows only. Five distinct managers hold a long common position at June 30, 2026, totalling 14,769,005 shares worth $1,203,821,597, with a direction count of 1 INCREASED, 2 UNCHANGED, 1 DECREASED and 1 NEW, and no option rows. Avoro Capital Advisors' share of the stake is 76.9% = 11,355,555 / 14,769,005, at an 8.31% portfolio weight; the top two holders (Avoro Capital Advisors and Baker Bros. Advisors) hold 13,348,338 shares, 90.4% of the stake. Debt-CUSIP rows, excluded from every share count: on CUSIP 04280AAC4, Howard Marks - Oaktree Capital Management reports a convertible bond valued at $10,951,820 on 9,146,000 of principal (labelled DECREASED) and Deerfield Management reports a note valued at $240,537,600 on 200,000,000 of principal (labelled UNCHANGED); the "shares" field on those rows is a principal amount, not a share count. Four of the five common holders are continuing holders, and all four verify row by row against the first quarter under two independent methods that agree exactly. Under the rule used in the previous audits — a holder's first-quarter row accepted only when its implied shares-change reproduces the EDGAR shares-change label at one decimal place — the verified continuing total is 14,291,079 shares at March 31 moving to 14,762,393 at June 30 (+3.3%): Avoro Capital Advisors 10,699,999 → 11,355,555 (+6.1%), Baker Bros. Advisors 1,992,783 → 1,992,783 (0.0%), Deerfield Management 1,573,297 → 1,389,055 (-11.7%), Edgewood Management 25,000 → 25,000 (0.0%). Because two recent audits found the generic accession-prefix method failing on shared filing-agent prefixes, the check was also rerun identifying filings by accession (filing total equal to the manager's collection total, unique) and pairing second- and first-quarter filings of the same manager by maximum CUSIP-set overlap under the same agent prefix (Baker Bros. Advisors overlap 76 CUSIPs, Deerfield Management 69, Edgewood Management 84, Avoro Capital Advisors 23 — each uniquely the maximum); the corrected method returns the identical four first-quarter rows, so no correction changes any figure here. The pipeline register then reconciles in both quarters once the new and exited rows are counted (first quarter: 5 rows and 14,876,761 shares = the verified continuing total of 14,291,079 plus RTW Investments' exited 585,682 shares; second quarter: 5 rows and 14,769,005 shares = the verified continuing 14,762,393 plus Polen Capital Management's new 6,612 shares; the register change is -0.7%, against the continuing cohort's +3.3%). Implied per-share value: every common row implies $81.51, the June 30, 2026 close, so the cohort implied price is $81.51, 0.0% against the close. One tracked manager (RTW Investments) exited, and one holder (Polen Capital Management) is labelled NEW.
• Full-market lens: SEC Form 13F Data Sets full-market aggregation. The primary table is the full13f collection's by-ticker file (holders = distinct filers reporting the ticker's CUSIP; 498 reported long positions out of 505 filers). Arrowhead carries a single CUSIP in this aggregation (04280A100), and the backfill fixtures' by-CUSIP row matches the by-ticker row exactly on every field — holders (505), long holders (498), shares (119,163,036), reported value ($9,711,116,012), prior holders (431) and prior reported value ($6,692,245,827). The by-ticker file's entered/exited fields (480 and 406, a net of +74 that matches the change in holder count) are gross flows, so this audit headlines the net change. Reported-value caution: the aggregate value ($9,711,116,012 over 119,163,036 shares) implies $81.49 per share against a June 30, 2026 close of $81.51 in our price file, a gap of -0.02% computed from the unrounded implied price. The aggregate sums the VALUE of every information-table row — including put and call option rows — while the share count covers long common-stock rows only, so we headline filer and share counts and label dollar values "reported."
• Insider lens: full-parse Form 4 aggregation (agg_by_ticker), record as of October 2, 2026 (44 filings). Sale and purchase counts are transaction-code counts (S and P) in non-derivative rows; grants and exercises are not counted as purchases, and one filing can contain many transaction rows. The 90-day window (July 5 to October 2, 2026) holds 0 purchase transactions and 2 sale transactions (13,600 shares, $1,186,600.00, 0 buyers, 2 sellers, 0 officer sale transactions) across 2 filings. The one-year window (October 3, 2025 to October 2, 2026) holds 0 purchases and 65 sales (580,501 shares, $38,044,096.32, 10 sellers, 50 officer sale transactions) across 31 filings, and the full record holds 0 purchases and 88 sales (1,240,607 shares, $49,169,314.58, 11 sellers, 72 officer sale transactions). The site's insider aggregate (90-day window, as of October 18, 2026) matches the full parse's 90-day window exactly: 0 purchases, 2 sale transactions, 2 sellers and $1,186,600.00 of sale value. This audit uses the full-parse numbers, which the site aggregate confirms for the 90-day window. Window price checks on our price file: the sales imply $87.25 per share in the 90-day window, inside its close range ($64.19 to $89.59); $65.54 over one year, inside its range ($35.41 to $89.59); and $39.63 over the full record, inside its full-period range — so dollar totals are cited for every window.
• 13D/G lens: full-parse SC 13D/G parsed filings (18 filings matching issuer CIK 879407 on CUSIP 04280A100: 2 SC 13D family filings — 1 SC 13D and 1 SC 13D/A — 6 SC 13G and 10 SC 13G/A, 11 of them amendments), filings through August 14, 2026. The site aggregation carries this name under a ticker-keyed row; that row (18 filings, 2 D-filings, 16 G-filings, 11 amendments, 11 reporters, latest date August 14, 2026, maximum 15.0%, total reported 239,610,029.5 shares) matches the parsed filings on filings, form mix, amendments, latest date, maximum and the cross-date reported total. The total sums reporter rows across filings and dates, so it is a filing-volume total, not a stake; joint reporters on one stake (Avoro Capital Advisors LLC and Behzad Aghazadeh; Sarepta Therapeutics, Inc. and Sarepta Therapeutics Investments, Inc.; FMR LLC and Abigail P. Johnson) each print the same share count and are not summed. The maximum of 15.0% is BlackRock, Inc.'s print of 20,323,221 shares as of December 31, 2025 (filed January 21, 2026, SC 13G/A); its later prints are 17,104,084 shares (12.2%) as of March 31, 2026 and 14,232,545 shares (10.1%) as of June 30, 2026. The SC 13D family prints are Sarepta's: 11,926,301 shares at 9.5% as of February 7, 2025 (SC 13D, filed February 14, 2025) and 0 shares at 0.0% as of August 13, 2025 (SC 13D/A, filed August 15, 2025). The latest filing prints Avoro Capital Advisors LLC and Behzad Aghazadeh at 13,823,383 shares each (9.64%) as of June 30, 2026 (filed August 14, 2026, SC 13G/A). Other filings with a March 31, 2026 event date print FMR LLC and Abigail P. Johnson at 7,349,106.75 shares each (5.2%), Vanguard Portfolio Management at 7,269,957 shares (5.19%) and Vanguard Capital Management at 7,081,293 shares (5.05%). The Vanguard Group name printed 15,525,072 shares (11.24%) as of June 30, 2025 and 0 shares at 0.0% as of March 13, 2026; the Vanguard names are reported exactly as they appear in each file and are not summed. The parsed coverage for this issuer holds these 18 filings; a 5% holder that has not filed in the covered window would not appear here.
• Congress lens: Senate PTR archive and House PTR archive as maintained on this site. The combined record (as of October 3, 2026) carries no row for this name; the House aggregate (as of October 3, 2026) carries no row; the Senate aggregate (as of October 1, 2026) carries no row. The absence is recorded as it stands in all three files: no recorded congressional transaction for this name sits in any of the archives as we hold them.
• Short interest lens: FINRA Equity Short Interest files (biweekly settlement dates), collected directly from FINRA's public distribution. This is the standard single-symbol case: the series is every row under symbol ARWR, all 137 of them under the single issuer name "Arrowhead Pharmaceuticals, Inc" exactly as printed in the files (the market-class column reads NNM on every row), covering 137 settlements from January 15, 2021 (5,232,192 shares) to September 15, 2026, with all 137 settlement dates distinct. The latest reading is 9,272,290 shares on September 15, 2026, down 1.64% from the prior settlement (9,426,449 on August 31, 2026), up 10.0% from the June 30, 2026 settlement of 8,430,780 and down 21.8% from the year-ago settlement of 11,862,693 on September 15, 2025, at 5.15 days to cover. The series maximum is 13,527,313 on April 30, 2025 and the series minimum is 2,673,812 on December 31, 2021. Series discontinuity check — no large step: no single-settlement step in the series reaches 2 times (the largest step is 1.190x, on March 15, 2023) and no step falls to 0.5 times or below (the smallest step is 0.718x, on June 30, 2026). One row in the series carries a FINRA revision flag ("R") — June 15, 2021, at 4,447,703 shares — and no row carries a stock-split flag; the flagged row sits between ordinary readings and is not connected to any step. The full series is published as collected, with no smoothing or rebasing. The recent path runs 8,430,780 (June 30), 9,635,297 (July 15), 9,656,078 (July 31), 9,207,426 (August 14), 9,426,449 (August 31) and 9,272,290 (September 15). FINRA publishes each settlement about two weeks after the fact, so the October price action is not yet in this series. The share-count ratio (6.56%) uses the fundamentals file's shares-outstanding figure below.
• Fundamentals note: our fundamentals collection carries Arrowhead's revenue of $829,448,000, net income of -$1,631,000 and assets of $1,385,295,000, all sourced to the same financial-series cache and all labelled fiscal 2025 — this name carries no fiscal-vintage split, so the three figures are reported here under their shared label. The file is marked ok for this name, with no missing fields: shares outstanding of 141,254,467 (sourced in the file to the DEI entity-common-stock shares-outstanding count, with a shares-end date of July 30, 2026) and a file-computed market value of $8,692,800,028.50. The file does not flag the issuer as a foreign private issuer, and it carries SIC 2834, Pharmaceutical Preparations, and a Nasdaq listing. The file's price for the name is $61.54 as of October 6, 2026; our daily-close file ends October 2, 2026 at $64.19, and we keep the two files' figures separate rather than blending them.
• Prices: our own daily-close file for ARWR through October 2, 2026 ($64.19 close, -3.3% year to date on that file; the 252-session closing high is $89.59 on August 4, 2026, so the last close sits 28.4% below it; the 252-session closing low is $34.60 on October 2, 2025, so the last close sits 85.5% above it; closes of $62.70 at March 31, 2026 and $81.51 at June 30, 2026, a second-quarter change of +30.0%; change from June 30 to October 2 of -21.2%; change from the September 30, 2025 close of $34.49 of +86.1%). The series in our price file begins June 1, 2021 at $71.91 and holds 1,342 rows.
• Market context sources: the TipRanks Trending Stocks by Analyst screener (full-page crawl, October 18, 2026), on which Arrowhead Pharmaceuticals followed SCHW, SMTC and BAC at the top of the page's order and covered names (RKLB, JBHT, USB, BNY, MSFT, VSTM, BLK, CRWV, PGR, META and UNH) and skipped names (IBKR, TSM and PNC, skipped as recorded in earlier runs), and was listed as a Strong Buy with a price target of $109.00 (94.99% upside as printed), 4 Buy, 0 Hold and 0 Sell ratings, a market value of $7.90B as printed, in Healthcare, dated October 15, 2026 on the page; and the Google Trends United States daily list (CyberKendra snapshot, last updated October 18, 2026, 7:18 PM IST), whose top ten were led by a celta de vigo - alavés query and carried no single-stock query. Figures we could not confirm were left out; the external items above are reported speech from those outlets, not GetCoattail measurements, and none of their price figures are cited in this audit beyond the screener's printed target and market value as reported in The Hype.
• Arrowhead Pharmaceuticals is in the GetCoattail stock-page universe: Arrowhead Pharmaceuticals (ARWR) stock page. Series data: arwr_lens_data.csv · arwr_short_interest_series.csv. Earlier audits: Targa Resources · Verastem · BNY.

Past patterns are not a promise of future results. For education only — not investment advice.

This article describes public filings as of the dates stated. It is not investment advice and makes no recommendation. Filings lag reality: 13F positions are as of June 30, 2026, and later trading is not yet public.

Revision history: v1.0 — October 18, 2026: first publication.