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X4 Pharmaceuticals

XFOR on Nasdaq. X4 Pharmaceuticals sells an oral drug to people with WHIM syndrome, a rare immune disorder. Market value $288m.

Watch this stockFree. We tell you when something changes.

Price checks use the past 12 months to June 2026. Some use the latest annual report instead, as marked. Quality checks use five annual reports, the latest for the year to December 2025.

Should I look at this?

Not a fit for our list right now

Why it could be worth it

What to watch out for

See Health care stocks that passed both tests

This is not advice. Check the numbers below.

Compare with another stock

Cash yield
annual report to December 2025
-31.2%low

For every $100 of what the whole company costs, it produced $-31.18 of spare cash last year. A savings account pays about $4.

Price to profit
past 12 months to June 2026
n/a

The filings do not give us enough to work this out.

Return on capital
five annual reports to December 2025
-280.6%five-year median

Each dollar kept in the business earns -281 cents a year. Above 10 is good.

Quality score: 40 of 100. Price score: 0 of 100. Our list needs 70 on quality and 60 on price.

$2.77 a share, 3% above its 1-year low

Over the past year the price has ranged from $2.70 to $4.83.

Pays no dividend

Prices from Tuesday’s close (6 October).

Five years of cash, in billions

-0.1
-0.1
-0.1
-0.1
-0.1
20212022202320242025
Revenue
$0$0$0$3m$7m
Operating margin
n/an/an/a-1400.0%-1336.7%
Debt to equity
0.530.451.083.390.40
Shares outstanding
0.07bn0.17bn0.17bn0.09bn0.10bn

Health checks

  • Free cash flow positive0 of 5 years
  • Accounting checksSkipped: company is not yet profitable
  • Debt0.40× equity
  • Revenue growth, five yearsStrong, 16.7% a year
  • Buying back its own sharesNo, 43% more shares since 2021

The quarter to June 2026

How the business did, compared with the same quarter a year earlier.

  • Sales: $2 million last quarter, about the same as a year ago.
  • A loss of $16 million, compared with a loss of $26 million a year ago.
  • It loses 1022 cents on each $1 of sales, compared with 2253 cents a year earlier.
  • 1604% more shares than a year ago. Each share owns a bit less of the company.
  • It has $120 million more cash than debt. A year ago debt was $36 million more than cash.
  • Sales grew on a year ago in each of the last 4 quarters.
Sales by quarter
Sales by quarter
Quarter toAmount
September 2024$560,000
December 2024$2m
March 2025$900,000
June 2025$2m
September 2025$2m
December 2025$2m
March 2026$3m
June 2026$2m
Profit by quarter
Profit by quarter
Quarter toAmount
September 2024-$37m
December 2024-$40m
March 2025$282,000
June 2025-$26m
September 2025-$30m
December 2025-$24m
March 2026-$20m
June 2026-$16m

From the company's quarterly reports to the SEC.

Dates

Next results (estimated)
n/a
Last annual report (10-K)
17 March 2026
Next quarterly (estimated, 10-Q)
5 November 2026

Who owns it

None of the long-term investors we follow own it. 89 funds in all.

Jun '25
Dec '25
Jun '26
Largest holders overall

From 13F filings for the quarter ended 30 June 2026.

Big holders and activists

17 investors own more than 5%.

  • Morgan Stanley
    Passive investor
    at least 10.2%+0.8 pts
    (filed with 2 related holders)
    Since 28 February 2026
  • at least 10.0%0.0 pts
    (filed with 1 related holder)
    Since 31 December 2025
  • Hoe Martin D.
    Passive investor
    10.0%
    Since 30 September 2025
  • Coastlands Capital Partners LP
    Passive investor
    at least 10.0%0.0 pts
    (filed with 3 related holders)
    Since 3 October 2025
  • Coastlands Capital LP
    Passive investor
    at least 10.0%
    (filed with 3 related holders)
    Since 11 August 2025
    What they said

    Concurrent with the August 2025 Financing, the Issuer's board of directors (the "Board") approved (i) the termination of each of the Chief Executive Officer and Chief Financial Officer of the Company and (ii) the appointment of an Executive Chairman, a new Chief Financial…

    Read the filing
  • Bain Capital Life Sciences Fund II, L.P.
    at least 10.0%
    (filed with 2 related holders)
    Since 11 August 2025
    What they said

    Concurrent with the August 2025 Financing, the Issuer's board of directors (the "Board") approved (i) the termination of each of the Chief Executive Officer and Chief Financial Officer of the Company and (ii) the appointment of an Executive Chairman, a new Chief Financial…

    Read the filing
  • FMR LLC
    Passive investor
    at least 9.7%−5.1 pts
    (filed with 1 related holder)
    Since 31 October 2025
  • Deep Track Capital, LP
    Passive investor
    at least 8.3%−1.7 pts
    (filed with 3 related holders)
    Since 30 June 2026
  • Perceptive Advisors LLC
    Passive investor
    at least 8.1%+0.8 pts
    (filed with 2 related holders)
    Since 30 June 2026
  • BCLS II Equity Opportunities, LP
    Passive investor
    at least 7.4%−2.6 pts
    (filed with 5 related holders)
    Since 31 December 2025
  • at least 7.4%
    (filed with 1 related holder)
    Since 24 October 2025
  • Growth Equity Opportunities 18 VGE, LLC
    Passive investor
    at least 6.2%−3.8 pts
    (filed with 11 related holders)
    Since 27 October 2025
    What they said

    GEO acquired the GEO Shares for investment purposes. Information with respect to the Offering set forth in Item 3 above is incorporated herein by reference to the extent responsive to this Item 4. Subject to the foregoing, depending on market conditions, its continuing…

    Read the filing
  • BlackRock, Inc.
    Passive investor
    5.9%+2.9 pts
    Since 30 June 2026
  • at least 5.8%−4.1 pts
    (filed with 2 related holders)
    Since 31 December 2025
  • Venrock Healthcare Capital Partners III, L.P.
    Passive investor
    at least 5.6%
    (filed with 6 related holders)
    Since 14 September 2026
  • BVF PARTNERS L P/IL
    Passive investor
    at least 3.9%−6.0 pts
    (filed with 9 related holders)
    Since 31 December 2025
  • at least 2.8%−7.2 pts
    (filed with 2 related holders)
    Since 31 December 2025
  • The Vanguard Group
    Passive investor
    Sold down below 5%
    Since 31 December 2024
  • ORBIMED ADVISORS LLC
    Passive investor
    Sold down below 5%
    Since 30 June 2025

From Schedule 13D and 13G filings: anyone owning more than 5% must file one.

What insiders did

In the last 12 months, 1 insider bought $249,997 of shares on the open market. 3 sold $462,907.

  • KIRSKE DAVID
    Chief Financial Officer
    Sold
    Date
    1 October 2026
    Shares
    11,767
    Price
    $2.86
    Value
    $33,658
  • Volpone John
    President
    Sold
    Date
    12 August 2026
    Shares
    24,576
    Price
    $4.44
    Value
    $109,228
  • Craig Adam R
    Executive Chairman, Director
    Sold
    Date
    12 August 2026
    Shares
    47,436
    Price
    $4.44
    Value
    $210,829
  • KIRSKE DAVID
    Chief Financial Officer
    Sold
    Date
    30 June 2026
    Shares
    8,543
    Price
    $4.26
    Value
    $36,428
  • KIRSKE DAVID
    Chief Financial Officer
    Sold
    Date
    12 May 2026
    Shares
    16,961
    Price
    $4.29
    Value
    $72,763
  • Craig Adam R
    Executive Chairman, Director
    Bought
    Date
    23 October 2025
    Shares
    86,206
    Price
    $2.90
    Value
    $249,997

From Form 4 filings: insiders must report trades in their own company's shares within two days.

What could go wrong

Cheap for a reason is the question the numbers cannot answer.

Whether the price already reflects the risks is what the deep dive is for.

The deep dive

Everything above is arithmetic on public filings. The deep dive reads the last ten years of annual reports, the proxy statements, and the earnings calls, then argues the case the way Buffett, Klarman, and Hohn would, and checks every claim against the source.

  • What the business is worth, as a range, and the margin of safety at today’s price
  • Prices to start buying, buy, and buy hard
  • The three things that would make this a mistake
  • Every number footnoted to the filing it came from
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What a finished deep dive looks like

Not advice. Numbers on this page come from SEC filings and are updated each night; prices are updated again after the US market closes. The five-year figures are rounded.