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Protagonist Therapeutics

PTGX on Nasdaq. Protagonist Therapeutics licenses oral drugs for inflammatory diseases to Johnson & Johnson. Market value $9.1bn.

Watch this stockFree. We tell you when something changes.

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

We can't read total debt from the filing, so debt is left out.

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
past 12 months to June 2026
1.5%low

For every $100 of what the whole company costs, it produced $1.46 of spare cash in the past 12 months. 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
n/a

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

Quality score: 48 of 100. Price score: 29 of 100. Our list needs 70 on quality and 60 on price.

$138.69 a share, 123% above its 1-year low

Over the past year the price has ranged from $62.24 to $160.81.

Pays no dividend

Prices from Tuesday’s close (6 October).

Five years of cash, in billions

-0.1
-0.1
-0.1
0.2
0.1
0.1
2021202220232024202512 monthsto Jun '26

Spare cash swings from quarter to quarter here: $131 million in the past 12 months, $56 million in the year to December 2025.

Revenue
$27m$27m$60m$434m$46m
Operating margin
-460.0%-494.2%-156.1%58.2%-343.6%
Debt to equity
n/an/an/an/an/a
Shares outstanding
0.05bn0.06bn0.06bn0.06bn0.06bn

Health checks

  • Free cash flow positive2 of 5 years
  • Accounting looks honest (Beneish)Not enough data
  • Financial strength (Piotroski)3 of 7 checks we could run
  • Profit backed by cash (accruals)No
  • DebtUnknown
  • Revenue growth, five yearsSlow, 10.0% a year
  • Buying back its own sharesNo, 32% more shares since 2021

The quarter to June 2026

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

  • Sales: $213 million last quarter, up 3749% on a year ago.
  • Profit: $163 million, after a loss of $35 million a year ago.
  • It keeps 21 cents of each $1 of sales as operating profit, up from 11 cents a year earlier.
  • Spare cash over the past 12 months: $131 million, up from $37 million.
  • 12% more shares than a year ago. Each share owns a bit less of the company.
  • Sales grew on a year ago in 3 of the last 4 quarters.
Sales by quarter
Sales by quarter
Quarter toAmount
September 2024$5m
December 2024$171m
March 2025$28m
June 2025$6m
September 2025$5m
December 2025$7m
March 2026$56m
June 2026$213m
Profit by quarter
Profit by quarter
Quarter toAmount
September 2024-$33m
December 2024$132m
March 2025-$12m
June 2025-$35m
September 2025-$39m
December 2025-$44m
March 2026$4m
June 2026$163m

From the company's quarterly reports to the SEC.

Dates

Next results (estimated)
n/a
Last annual report (10-K)
25 February 2026
Next quarterly (estimated, 10-Q)
4 November 2026

Who owns it

2 long-term investors we follow own it, down from 3 last quarter. 347 funds in all.

Jun '25
Dec '25
Jun '26

Sold out this quarter

Largest holders overall

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

Big holders and activists

9 investors own more than 5%.

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

What insiders did

No insider bought shares on the open market in the last 12 months. 7 sold $89m, $53m of it under preset trading plans.

  • Ali Asif
    Chief Financial Officer
    Sold
    under a preset trading plan
    Date
    30 September 2026
    Shares
    58,629
    Price
    $141.78
    Value
    $8m
  • PATEL DINESH V PH D
    President and CEO, Director
    Sold
    under a preset trading plan
    Date
    10 September 2026
    Shares
    7,278
    Price
    $144.10
    Value
    $1m
  • PATEL DINESH V PH D
    President and CEO, Director
    Sold
    under a preset trading plan
    Date
    9 September 2026
    Shares
    63,548
    Price
    $146.18
    Value
    $9m
  • PATEL DINESH V PH D
    President and CEO, Director
    Sold
    under a preset trading plan
    Date
    8 September 2026
    Shares
    54,174
    Price
    $145.87
    Value
    $8m
  • PATEL DINESH V PH D
    President and CEO, Director
    Sold
    under a preset trading plan
    Date
    11 August 2026
    Shares
    34,239
    Price
    $148.52
    Value
    $5m
  • PATEL DINESH V PH D
    President and CEO, Director
    Sold
    under a preset trading plan
    Date
    10 August 2026
    Shares
    65,761
    Price
    $149.11
    Value
    $10m
  • Waddill William D.
    Director
    Sold
    under a preset trading plan
    Date
    23 June 2026
    Shares
    9,000
    Price
    $117.94
    Value
    $1m
  • Waddill William D.
    Director
    Sold
    under a preset trading plan
    Date
    10 June 2026
    Shares
    9,000
    Price
    $107.68
    Value
    $969,120
  • Waddill William D.
    Director
    Sold
    under a preset trading plan
    Date
    29 May 2026
    Shares
    9,000
    Price
    $99.64
    Value
    $896,760
  • PATEL DINESH V PH D
    President and CEO, Director
    Sold
    under a preset trading plan
    Date
    12 May 2026
    Shares
    75,000
    Price
    $100.12
    Value
    $8m

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

Warning signs in its filings

Problems the company itself reported to the SEC, in its own words.

None of the serious warning signs we check for were found. 1 thing worth knowing.

We look for five warning signs: doubt it can keep going, weak checks on its own accounts, a notice that its past accounts can't be relied on, a change of auditor, and one customer bringing in a big share of sales. We don't check lawsuits, investigations or debt yet.

We checked the auditor's report, internal controls, restatement notices, auditor changes and big customers in the 10-K filed 25 Feb 2026, plus the 10-Q filed 5 Aug 2026 and 3 later 8-Ks.

  • One big customer

    Worth knowing

    One customer brings in a big share of sales: 100% last year. Losing that customer would hurt.

    “For the year ended December 31, 2025, Takeda accounted for 100 % of the Company’s revenues.”

    From the 10-K filed 25 February 2026, Item 8. Financial Statements and Notes. Read it in the filing

A 10-K is the yearly report every US company files with the SEC. An 8-K is a short notice of a big event.

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.