8-K vs 6-K vs press release: where catalyst dates are disclosed

Look down the Source column of our tracker and you'll see the same few labels again and again: "8-K exhibit 99.1", now and then "6-K", and occasionally "Press release". They aren't interchangeable. Each is a different kind of document with different rules, and knowing which one you're reading helps you judge how much weight a date can bear.

The Form 8-K

A Form 8-K is a "current report" that US public companies file with the SEC to announce significant events between their quarterly and annual reports. The form's instructions list numbered items, each for a type of event, and most items must be filed within four business days of the event.

The items that matter most for biotech catalysts are:

Item 2.02, Results of Operations and Financial Condition. The quarterly results press release. In biotech it nearly always includes a "recent highlights and upcoming milestones" section, which is where most readout windows and many PDUFA dates are restated.
Item 7.01, Regulation FD Disclosure. Used to put information out publicly under Regulation FD, such as an investor presentation or a press release the company wants on the record.
Item 8.01, Other Events. A voluntary item for anything the company considers important to shareholders. Trial results and FDA news often go here.
Item 9.01, Financial Statements and Exhibits. Lists the attached documents, such as the Exhibit 99.1 press release.

No 8-K item specifically requires a company to announce a PDUFA date or a trial result. Companies disclose them because the information is material, and because once they've told anyone outside the company, Regulation FD obliges them to tell everyone.

From the tracker

When this guide was written, about seven in ten of the tracker's rows were sourced from filings made between late July and mid-August 2026, which is second-quarter results season. That's not a coincidence: the Item 2.02 results release is the one document where nearly every biotech restates its upcoming milestones, every quarter. It's why the weekly scan is heaviest in the weeks after each results season.

Furnished versus filed

Information under Items 2.02 and 7.01 is, by default, "furnished" rather than "filed". That's a legal distinction: furnished information isn't subject to the same liability under section 18 of the Securities Exchange Act, and it isn't automatically incorporated into the company's other SEC documents. Item 8.01 information is filed. For a reader it rarely changes what a date means, but it explains why companies often put their more promotional material under 7.01.

Exhibit 99.1: the part you actually read

The 8-K form itself is usually a page or two of boilerplate naming the items. The content is in the exhibits, and the press release is almost always Exhibit 99.1. Investor presentations often appear as 99.1 or 99.2, and their "milestones" slides are a common source of readout windows. That's why our Source column says "8-K exhibit 99.1": we link to the document with the actual sentence in it, not to the cover form.

The Form 6-K

Companies that qualify as "foreign private issuers", usually headquartered outside the US, don't file 8-Ks. They furnish Form 6-K instead. A 6-K covers information the company makes public in its home country, files with a foreign stock exchange, or sends to its shareholders. There's no fixed list of items and no four-day deadline; the rule is to furnish it promptly.

In practice, a biotech's 6-K looks much like an 8-K: a short cover page and the press release as an exhibit. Foreign issuers file an annual report on Form 20-F rather than a 10-K and aren't required to file quarterly reports, so the 6-K results release can be the only interim update. Some foreign companies choose to file 8-Ks and 10-Qs like US companies anyway.

From the tracker

PolyPid's PDUFA date for D-PLEX100 comes from a 6-K exhibit, as do the dates for Belite Bio's tinlarebant (Belite page) and Pharvaris's deucrictibant (Pharvaris page).

The press release on its own

Companies publish press releases through newswire services and on their own websites, and most material ones are also filed or furnished on an 8-K or 6-K. But not all. A company may judge that an announcement isn't material enough for a filing, or rely on a widely distributed release alone to satisfy Regulation FD. Foreign regulatory approvals and news from private partners are common examples.

A press release without a filing is still a primary source: it's the company's own words. But it has no SEC filing date, and web pages can be edited. Where our row links to a press release, the note says whether we looked for a matching filing and didn't find one.

From the tracker

Palvella's completed NDA submission and Insmed's approval in Japan both link to press releases. Each row's note records that no matching 8-K was found in EDGAR full-text search when it was checked (Palvella page, Insmed page).

Other places dates appear

10-Q and 10-K. The quarterly and annual reports restate milestones, often more cautiously than the press release, and their risk factors describe what could delay them. Useful for confirming that guidance hasn't changed.
Investor conferences. Presentations at events like January's J.P. Morgan Healthcare Conference are often furnished on an 8-K under Item 7.01, and timelines are frequently updated there.
Catalyst calendars and news sites. Secondary. Useful for discovering a date, never for confirming one. Our rows sourced this way are labelled Reported until someone finds the company's own document.

How much weight each source bears

An FDA document, such as an approval notice or an advisory committee calendar entry, where one exists.
An 8-K or 6-K exhibit: the company's own words, fixed in time by the filing date.
A company press release with no matching filing: the company's own words, but without the SEC timestamp.
A secondary source: a lead to follow up, not a source to rely on.

Whichever it is, the most recent one wins. A date in an August 8-K is superseded by a different date in a September 8-K. How to verify a date on EDGAR walks through finding the latest.

More guides

What a PDUFA date is, and why the FDA doesn't publish themThe PDUFA target action date is the FDA's own deadline for deciding on a drug application. Here is where it comes from, how it moves, and why you only hear about it from the company.
What happens at an FDA advisory committee meetingWho sits on an FDA advisory committee, how the day runs, what the vote means and doesn't mean, and where to find the documents beforehand.
What a Complete Response Letter means, and what usually followsA Complete Response Letter is the FDA's "not yet" on a drug application. What it contains, the company's options, how resubmission clocks work, and how to read the announcement.
How to read a Phase 3 topline readoutEndpoints, p-values, effect sizes, safety tables and the phrase "met its primary endpoint": a practical guide to reading the press release a company puts out when pivotal trial results land.
Clinical trial phases explained: Phase 1 to Phase 4What each phase of clinical development is for, roughly how big the trials are, what the in-between labels like 1b, 2a and 2/3 mean, and what a readout at each stage can and can't tell you.
NDA vs BLA: the two kinds of US drug applicationWhy some products are filed as a New Drug Application and others as a Biologics License Application, who reviews each, what supplements and rolling submissions are, and why the difference matters after approval.
Fast Track, Breakthrough, Priority Review and Accelerated Approval explainedThe FDA's expedited programmes are often lumped together, but they do different things at different stages. What each one is, what it changes about the timeline, and what it doesn't promise.
How to verify a catalyst date yourself on SEC EDGARA step-by-step walkthrough of the method behind this site: finding the filing that announced a PDUFA date or readout window, reading it properly, and spotting the traps that catalyst calendars fall into.
Why catalyst windows like "H2 2026" are vague, and how they narrowMost biotech catalysts don't have a date, only a window the company guided to. Why that is, what the common phrases mean, how windows tighten or slip, and how this site handles them.
Glossary of FDA and biotech catalyst termsPlain-English definitions of the regulatory, clinical and SEC-filing terms used across the tracker and the guides, from AdComm to Type A meeting.