Five of 147: Samantha McLemore - Patient Capital Management Is 30.7% of the Superinvestors' Biogen Stake. Perceptive Advisors Is New at 29.9%.

GetCoattail Research — The Filing Tape #114. Biogen drew an upgrade this week — a JPMorgan analyst moved the stock to Buy on a story broadening beyond its Alzheimer's drug Leqembi — and the filings describe a register in rotation: 5 of the 147 superinvestors hold the common stock, the top holder at 30.7% after a 25.3% cut, a new holder at 29.9%, continuing holders verified down 13.8%, a separate call position up 9,900.0% in underlying shares, insiders with two purchases in the full record, and short interest at 3.96% of shares outstanding.

The Hype

Biogen's attention this week is an upgrade story. The stock appeared third, in title order, in TipRanks' weekend update "OCUL, IDXX, BIIB, BFLY, TMUS Trending With Analysts" — published October 17, 2026 — after analyst Chris Schott of JPMorgan upgraded the stock to Buy, on a story described as broadening beyond the Alzheimer's drug Leqembi, with 2027 catalysts in felzartamab and litifilimab, readthroughs from Eli Lilly's TRAILBLAZER-ALZ-3 trial, and legacy multiple sclerosis declines being offset by new products. TipRanks Our price file describes a stock that ran into the quarter-end and held its ground: it rose 17.9% in the second quarter, from $183.33 on March 31 to $216.06 on June 30, then added 1.8% to close at $219.88 on October 2 — up 24.9% year to date, 3.9% below the 252-session closing high of $228.69 (September 28, 2026) and 54.6% above the 252-session low of $142.26 (October 16, 2025).

The Tape

For Biogen — the one hundred and fourteenth Filing Tape audit — the tape shows a five-holder cohort split almost evenly three ways at the top, its continuing holders verified down 13.8% while a new holder took 29.9% and the top holder's call position multiplied a hundredfold, a full market holding a fifth more shares, an insider record with two purchases against eight sales, a congressional row confined to the House, nine passive 5% filings headed by a rising 12.4% print, and a borrow at 3.96% of shares outstanding, 14.2% below its 2025 peak.

Lens 1 — the superinvestors: five holders, three near 30% each, a verified 13.8% cut by the continuing four, and one call row kept apart. 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 holding this name) — so all five holders sit on the June 30, 2026 period-end, on the common-stock CUSIP 09062X103, totalling 923,746 shares worth $199,584,616, long only. Samantha McLemore - Patient Capital Management is 30.7% of that stake: 283,697 shares worth $61,295,674 — at a 2.01% portfolio weight, decreased 25.3%. Sarah Ketterer - Causeway Capital Management holds 278,283 shares worth $60,125,780 — 30.1% of the stake — at a 0.65% weight, decreased 0.9%; the top two together are 60.8%. Perceptive Advisors holds 276,173 shares worth $59,669,938 — 29.9% of the stake — labelled NEW at a 0.90% weight — genuinely new: no first-quarter register row for this name sits under its filing prefix. OrbiMed Advisors holds 61,600 shares ($13,309,296), unchanged, at a 0.25% weight; Hillman Capital Management holds 23,993 shares ($5,183,928), down 18.8%, at a 3.75% weight. The four continuing holders verify row by row against the first quarter, moving from 751,664 shares at March 31 to 647,573 at June 30 (-104,091 shares, -13.8%); no tracked manager exited. One further row is reported separately and counted in no long total: Patient Capital Management also holds a call position on the call CUSIP 09062X903 — 189,400 underlying shares worth $40,921,764, labelled INCREASED at 9,900.0%, which reproduces exactly from its first-quarter register call row of 1,894 underlying shares. Every common-stock row implies exactly $216.06, the June 30 close. 13F figures are as of June 30, 2026, published up to 45 days later.

Lens 2 — institutions: 57 more filers holding a fifth more shares. At June 30, 2026, 1,045 institutions reported positions, up 57 from 988 at March 31 (+5.77%); 1,035 are long. Reported shares rose 20.74%, from 116,484,624 to 140,647,629 (+24,163,005 shares), and reported value rose 45.21% to $30,593,476,325, from $21,068,382,296, labelled "reported" because the aggregate includes option rows (see methodology). Flow counts agree: 942 entered, 885 exited, a net of +57. The name carries two CUSIPs here — the common stock and a call CUSIP whose row holds 5 filers, no long positions, no shares and $99,214,996 of reported value — and the reported value implies $217.52 per share against a June 30 close of $216.06, a gap of +0.68%.

Lens 3 — insiders: two purchases in the full record, one of them three shares. The parsed Form 4 record holds 73 filings through October 2, 2026. The last 90 days hold no purchase transaction at all against 2 sales: 1,186 shares for $239,749.90, by 1 seller, with no officer sale transaction in the window, across 2 filings. The one-year window holds 1 purchase — 3 shares for $585.11, by 1 buyer, an officer purchase — against 4 sales: 4,594 shares for $905,414.10, by 2 sellers, 2 of them officer sales, across 37 filings. Across the full record: 2 purchases totalling 1,238 shares for $152,144.31, by 2 buyers, 1 of them an officer purchase — against 8 sales totalling 19,900 shares for $3,069,213.86, by 4 sellers, 5 of them officer sales. Every window prices inside its range — 90-day sales imply $202.15, one-year purchases $195.04 and sales $197.09, full-record purchases $122.90 and sales $154.23 — so dollar totals are cited for every window.

Lens 4 — Congress: a small House row, and no Senate row. The combined record (as of October 3, 2026) carries a row: 2 members, 4 purchase transactions and 2 sale transactions, the last purchase on June 5, 2026, with both parties represented. The House aggregate (as of October 3, 2026) carries the identical row, and the Senate aggregate (as of October 1, 2026) carries no row — so every recorded transaction in our archives sits in the House file.

Lens 5 — the 5% register: nine filings, all passive, and the maximum is the newest print. Our full parse holds 9 SC 13D/G filings matching the site aggregate — 3 SC 13G and 6 SC 13G/A, 6 amendments, 7 reporter names in 13 reporter rows, no 13D at all. The register maximum is also the latest filing: FMR LLC and Abigail P. Johnson each report 18,294,523.51 shares (12.4%) as of June 30, 2026 (filed August 6, 2026, SC 13G/A), and the same pair's prints have risen at each filing — 6.4% as of December 31, 2025, 8.7% as of March 31, 2026, 11.3% as of May 29, 2026, then 12.4%. The remaining filings are PRIMECAP MANAGEMENT CO/CA/ at 14,954,697 shares (10.2%), BlackRock, Inc. at 12,506,681 shares (8.5%), Vanguard Capital Management at 10,989,562 shares (7.48%), STATE STREET CORPORATION at 7,321,168 shares (5.0%) and The Vanguard Group at 0 shares (0.0%), recorded as filed. The 160,108,311.72-share total counts reporter rows across dates, not distinct stakes.

Lens 6 — short interest: 3.96% of the share count, 14.2% below its 2025 peak, with no flagged step. The latest FINRA settlement, September 15, 2026, records 5,817,797 shares sold short — 3.96% of the 146,800,000 shares outstanding — at 7.59 days to cover, up 1.59% from the prior settlement (5,726,631 on August 31, 2026). The series maximum across 137 settlements is 6,777,473 on November 28, 2025, so the latest sits 14.2% below that peak; against the June 30, 2026 reading of 5,723,194 it is up 1.7%. The recent path runs 5,723,194 (June 30), 5,999,133 (July 15), 5,453,901 (July 31), 5,190,555 (August 14), 5,726,631 (August 31) and 5,817,797 (September 15). The series contains no single-settlement step at or above 2 times: the largest step is a ratio of 1.427 on December 31, 2024, so there is no discontinuity to flag in this series.

The Gap

The narrative arriving this week is a broadening story: an upgrade to Buy on a pipeline past Leqembi and readthroughs from a competitor's Alzheimer's trial. The filings describe tracked long money rotating rather than simply arriving. The stock rose 17.9% in the second quarter, and the four continuing tracked holders cut a verified 13.8% in it — the top holder cut 25.3% of its common position — while a genuinely new holder, Perceptive Advisors, took a 29.9% stake in the cohort and the top holder added a call position whose underlying share count multiplied a hundredfold. The broad market added a fifth more shares, the 5% register's largest holder has raised its print at four straight filings to 12.4%, insiders have bought twice in 73 filings — once for three shares — and the congressional record is two House members. One plausible reading is that the upgrade case rests on the pipeline calendar, while the June tape shows the tracked cohort repositioning into strength — common stakes trimmed at the top, conviction reappearing in a new name and an option row, not in the headline long count.

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). All five holders sit on a June 30 period-end, before the upgrade. Whether Perceptive Advisors' new 276,173-share position — 29.9% of the cohort — is still there, and whether Patient Capital Management's common-stock cut alongside its 189,400-underlying-share call position persists, decides whether this lens reads as rotation or exit.
• 2. A third insider purchase, at a size that registers. The record holds 2 purchases in 73 filings — 1,238 shares in total, and just 3 shares in the last year, against 8 sales. A further open-market purchase of material size would be only the third in the record, and the first that is not negligible.
• 3. A first Senate row. The Senate archive holds no row for this name; the combined and House aggregates hold the only congressional record (2 members, 4 purchases, 2 sales). A first recorded Senate transaction would open the blank half of this lens.
• 4. A fresh 5% print above 12.4%, or a first 13D. The register's maximum is its newest filing — the FMR LLC and Abigail P. Johnson print of 12.4% as of June 30, 2026, filed August 6, 2026 — the pair's fourth consecutive increase. A new filing moving the maximum, or a first 13D, would change this lens.
• 5. Short interest back through the November 2025 peak. The borrow stands at 5,817,797 shares, up 1.59% on the settlement and 14.2% below the November 28, 2025 peak of 6,777,473. A reading at or above 6,777,473 would set a new series high.

Related reading: Eight of 147: Terry Smith - Fundsmith Is 59.5% of the Superinvestors' June-Quarter IDEXX Stake. Its Insiders Have Never Bought a Share. — Filing Tape #113; Two of 147: Prem Watsa Is 56.8% of the Superinvestors' Domino's Pizza Stake. Its Insiders Have Never Bought a Share. — Filing Tape #112. Biogen's own page: Biogen (BIIB) 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 6, 2026; short interest through September 15, 2026; the price file ends October 2, 2026. Five 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, this name carries two CUSIPs — the common stock (09062X103) and a call-option CUSIP (09062X903) — and every headline share count in this audit is common-stock long only; the one call row in the tracked collection is reported separately wherever it appears and is never added to a long total. Third, in the full-market aggregation the two by-CUSIP holder counts sum to more than the distinct filer count, because 3 filers report both CUSIPs; the distinct count is used throughout (see the full-market note). Fourth, insiders have bought in this name — 2 purchase transactions in the full record — so no "never bought" claim is made; one of the two purchases is 3 shares, and the sizes are printed wherever the count appears. Fifth, the TipRanks article (October 17, 2026) postdates the 13F snapshot and the short-interest series; the article is known to this audit only from outside coverage, not from our own files, and none of its price figures — including the price target reported with the upgrade — are cited here; every 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); Biogen positions are counted on the common-stock CUSIP 09062X103, long rows only. Five distinct managers hold long positions, all at June 30, 2026, totalling 923,746 shares worth $199,584,616, with a direction count of 3 DECREASED, 1 NEW and 1 UNCHANGED. Samantha McLemore - Patient Capital Management's share of the stake is 30.7% = 283,697 / 923,746; Sarah Ketterer - Causeway Capital Management's is 30.1% = 278,283 / 923,746; Perceptive Advisors' is 29.9% = 276,173 / 923,746; the top two together are 60.8% of the stake and the top three 90.7%. All four continuing holders verify row by row against the first quarter under the rule used in the previous audits — a holder's first-quarter row accepted only when it sits under the same filing-agent prefix as the manager's second-quarter accession and its implied shares-change reproduces the EDGAR shares-change label at one decimal place — so the verified continuing total is 751,664 shares at March 31 moving to 647,573 at June 30 (-13.8%), with no unverified holder. The NEW-label register cross-check was run for the one NEW holder: Perceptive Advisors has no first-quarter register row for either CUSIP under its second-quarter filing prefix (0001012975), so its NEW label matches the register and the entry is genuine. The early-filer cross-check has no case to run — no September 30 holder exists for this name — and passes vacuously. Patient Capital Management's separate call row (CUSIP 09062X903, put/call flag "Call", class CALL) reports 189,400 underlying shares worth $40,921,764 at a 1.34% portfolio weight, labelled INCREASED at 9,900.0%; that label reproduces exactly against the pipeline first-quarter register, where the same manager's call row holds 1,894 underlying shares (189,400 / 1,894 − 1 = 9,900.0%). The call row is excluded from every long count, direction count and implied-price figure in this audit. The pipeline register reconciles in both quarters once the call rows are included (first quarter: 5 rows and 753,558 shares, equalling the verified continuing common total plus the first-quarter call row, 751,664 + 1,894; second quarter: 6 rows and 1,113,146 shares, equalling the verified continuing total plus the new holder plus the second-quarter call row, 647,573 + 276,173 + 189,400; the common-stock-only register change is +22.9%). Implied per-share value: all five common-stock rows imply exactly $216.06, the June 30, 2026 close, so the cohort implied price is $216.06, 0.0% against the close. No tracked manager exited.
• 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 CUSIPs; 1,035 reported long positions out of 1,045 filers). Biogen carries two CUSIPs in this aggregation (09062X103 and 09062X903), and the backfill fixtures' by-CUSIP rows sum to the by-ticker row exactly on shares (140,647,629), reported value ($30,593,476,325), prior reported value ($21,068,382,296) and long holders (1,035); on holder counts the by-CUSIP rows sum to 1,048 against the distinct 1,045 (prior: 990 against 988), because 3 filers report both CUSIPs (prior quarter: 2) and are counted once in the by-ticker file. The call CUSIP's own row holds 5 filers, 0 long holders, 0 shares and $99,214,996 of reported value. The by-ticker file's entered/exited fields (942 and 885, a net of +57 that matches the change in holder count) are gross flows, so this audit headlines the net change. Reported-value caution: the aggregate value ($30,593,476,325 over 140,647,629 shares) implies $217.52 per share against a June 30, 2026 close of $216.06 in our price file, a gap of +0.68% — printed here as found. 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 (73 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 (1,186 shares, $239,749.90, 0 buyers, 1 seller, 0 officer sale transactions) across 2 filings. The one-year window (October 3, 2025 to October 2, 2026) holds 1 purchase transaction (3 shares, $585.11, 1 buyer, 1 officer purchase transaction) and 4 sale transactions (4,594 shares, $905,414.10, 2 sellers, 2 officer sale transactions) across 37 filings. The full record holds 2 purchase transactions (1,238 shares for $152,144.31 by 2 buyers with 1 officer purchase transaction) and 8 sale transactions (19,900 shares for $3,069,213.86 by 4 sellers with 5 officer sale transactions). The site's insider aggregate (90-day window, as of October 17, 2026) carries a row for this name that matches the full parse's 90-day window exactly (site: 0 purchases, 2 sales, $239,749.90, 1 seller; insider_site_match_w90=true). Window price checks on our price file: the 90-day sales imply $202.15 per share, inside the 90-day close range ($191.95 to $228.69); the one-year purchases imply $195.04 and the one-year sales $197.09, inside the one-year close range ($142.26 to $228.69); the full-record purchases imply $122.90 and the full-record sales $154.23, inside the price file's full-period close range ($113.38 to $414.71) — so dollar totals are cited for every window.
• 13D/G lens: full-parse SC 13D/G parsed filings (9 filings matching issuer CIK 875045 on CUSIP 09062X103: 3 SC 13G and 6 SC 13G/A, 6 of them amendments, no SC 13D; no parsed filing sits on the call CUSIP), filings through August 6, 2026. The site aggregation carries this name under a ticker-keyed row; that row (9 filings, 0 D-filings, 9 G-filings, 6 amendments, 7 reporters, latest date August 6, 2026, maximum 12.4%, total reported 160,108,311.72 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 (13 reporter rows), so it is a filing-volume total, not a stake; four of the filings report the same shares twice, once under FMR LLC and once under Abigail P. Johnson. The filings are reported as filed, under the names exactly as they appear: FMR LLC and Abigail P. Johnson each printing 9,413,062.03 shares at 6.4% as of December 31, 2025 (filed February 5, 2026, SC 13G), each printing 12,807,541.5 shares at 8.7% as of March 31, 2026 (filed May 6, 2026, SC 13G/A), each printing 16,652,974.82 shares at 11.3% as of May 29, 2026 (filed June 5, 2026, SC 13G/A) and each printing 18,294,523.51 shares at 12.4% as of June 30, 2026 (filed August 6, 2026, SC 13G/A — the register maximum and the latest filing); PRIMECAP MANAGEMENT CO/CA/ printing 14,954,697 shares at 10.2% as of September 30, 2025 (filed November 13, 2025, SC 13G/A); BlackRock, Inc. printing 12,506,681 shares at 8.5% as of March 31, 2025 (filed April 17, 2025, SC 13G/A); Vanguard Capital Management printing 10,989,562 shares at 7.48% as of March 31, 2026 (filed April 29, 2026, SC 13G); STATE STREET CORPORATION printing 7,321,168 shares at 5.0% as of September 30, 2025 (filed November 10, 2025, SC 13G); and The Vanguard Group printing 0 shares at 0.0% as of March 13, 2026 (filed March 26, 2026, SC 13G/A). The parsed coverage for this issuer holds these 9 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 a row for this name (2 members, 4 purchase transactions, 2 sale transactions, last purchase June 5, 2026, both parties represented); the House aggregate (as of October 3, 2026) carries the identical row; the Senate aggregate (as of October 1, 2026) carries no row. The identical combined and House rows mean every recorded transaction for this name sits in the House archive as we hold it, and the Senate absence is recorded as it stands: no recorded Senate transaction for this name sits in that archive.
• Short interest lens: FINRA Equity Short Interest files (biweekly settlement dates), collected directly from FINRA's public distribution. The published series covers all 137 settlements under the symbol from January 15, 2021 (3,640,201 shares) to September 15, 2026. Every settlement row under the symbol is this issuer's row, under a single issuer-name variant across the file vintages — "Biogen Inc. Common Stock" on all 137 settlements (January 15, 2021 to September 15, 2026, with an NNM market-class code), recorded as printed; there are no other-issuer rows under the symbol. The latest reading is 5,817,797 shares on September 15, 2026, up 1.59% from the prior settlement (5,726,631 on August 31, 2026), down 14.2% from the series maximum of 6,777,473 on November 28, 2025 and up 1.7% from the June 30, 2026 reading of 5,723,194, at 7.59 days to cover. Series discontinuity check — none found: the largest single-settlement step in the series is a ratio of 1.427, on December 31, 2024, when the print rose from 2,576,781 (December 13, 2024) to 3,676,606; no step reaches 2 times, so there is no flagged step to disclose in this series. The series minimum is 1,707,680 shares on February 15, 2023. The recent path runs 5,723,194 (June 30), 5,999,133 (July 15), 5,453,901 (July 31), 5,190,555 (August 14), 5,726,631 (August 31) and 5,817,797 (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 (3.96%) uses the fundamentals file's shares-outstanding figure below.
• Fundamentals note: our fundamentals collection carries Biogen's revenue of $9,890,600,000, net income of $1,292,900,000 and assets of $29,439,500,000 — all three labelled fiscal 2025 in the file and all sourced to the same financial-series cache, so there is no vintage split to flag. The file is marked ok for this name, with no missing fields: shares outstanding of 146,800,000 (sourced in the file to the shares-outstanding count as of December 31, 2025, from the common-stock shares-outstanding line) and a file-computed market value of $32,720,251,910.40. The file does not flag the issuer as a foreign private issuer, and it carries SIC 2836, Biological Products, (No Diagnostic Substances), and a Nasdaq listing. The file's price for the name is $222.89 as of October 6, 2026; our daily-close file ends October 2, 2026 at $219.88, and we keep the two files' figures separate rather than blending them.
• Prices: our own daily-close file for BIIB through October 2, 2026 ($219.88 close, +24.9% year to date on that file; the 252-session closing high is $228.69 on September 28, 2026, so the last close sits 3.9% below it; the 252-session closing low is $142.26 on October 16, 2025, so the last close sits 54.6% above it; closes of $183.33 at March 31, 2026 and $216.06 at June 30, 2026, a second-quarter change of +17.9%; change from June 30 to October 2 of +1.8%; change from the September 30, 2025 close of $140.08 of +57.0%; change from the October 2, 2025 close of $155.25 of +41.6%; the December 31, 2025 close is $175.99; the September 30, 2026 close is $225.88). The series in our price file begins June 1, 2021 at $267.15 and holds 1,342 rows; the file's full-period close range is $113.38 to $414.71.
• Market context sources: the TipRanks weekend update "OCUL, IDXX, BIIB, BFLY, TMUS Trending With Analysts," published October 17, 2026, in which Biogen appeared third in title order — OCUL first, skipped in this series' selection for missing lenses; IDEXX second, published as Filing Tape #113; BFLY fourth, not reached; and TMUS fifth, already covered — with analyst Chris Schott of JPMorgan upgrading the stock to Buy, the story described as broadening beyond the Alzheimer's drug Leqembi, 2027 catalysts in felzartamab for antibody-mediated rejection (a potential market of over $2 billion in that indication alone, as reported) and litifilimab for cutaneous lupus (an indication with no approved therapies today, as reported), readthroughs from Eli Lilly's TRAILBLAZER-ALZ-3 trial, and legacy multiple sclerosis declines being offset by new products; the AltIndex StockTwits most-mentioned list refreshed on October 17, 2026, whose top names were already covered, skipped, crypto or index funds in this series; and the Google Trends United States daily list (CyberKendra snapshot updated October 18, 2026), whose top ten 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.
• Biogen is in the GetCoattail stock-page universe: Biogen (BIIB) stock page. Series data: biib_lens_data.csv · biib_short_interest_series.csv. Earlier audits: IDEXX Laboratories · Domino's Pizza.

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.