M&A SEC Filings: Every Form a Merger or Acquisition Triggers

A merger or acquisition does not produce one SEC filing; it produces a sequence of them, and which forms appear depends on whether the deal is paid in stock, cash or both, and whether a third party, the company itself, or an insider group is doing the buying. This post lists every form that shows up in a typical deal, in the order it is filed, with real counts from EDGAR's own index and a working API call for pulling them.

Why "the merger filing" is not one form

Public company deals are reported under rules written for different situations: Securities Act registration when new shares change hands, Exchange Act proxy rules when shareholders vote, and the tender offer rules when a buyer goes straight to shareholders with a cash offer. A single large acquisition can touch all three. A cash-only deal between the target's existing management and a private buyer runs through a narrower set built around disclosure to the target's own board and shareholders rather than new securities. Treating "M&A filings" as one form misses that the paperwork tracks how the deal is structured, not just that a deal is happening.

The filings a deal triggers, in order

Stock deals: S-4, F-4 and Rule 425

When the acquirer pays with its own stock, it has to register those new shares with the SEC before issuing them, using Form S-4 (or Form F-4 if the acquirer is a foreign private issuer). The S-4 includes the proxy statement the target's shareholders vote on, so it functions as both a registration statement and a proxy in one document; that combined document is often called a joint proxy statement and prospectus. Before the S-4 is ready, companies that want to talk publicly about the deal (in a press release, an investor call transcript or an employee memo) file that material under Rule 425, which lets them communicate about a proposed business combination without those statements being treated as an unregistered offer of securities.

Cash tender offers: Schedule TO and the 14D-9

A cash deal can skip the shareholder vote and registration process entirely if the acquirer makes a tender offer directly to shareholders. A third party acquirer files Schedule TO-T (an issuer repurchasing its own shares files TO-I instead), which sets out the offer price, the number of shares sought and the offer's expiration date, and must stay open at least 20 business days under Regulation 14D. The target company then has 10 business days to respond with its own filing, Schedule 14D-9, stating whether its board recommends shareholders accept the offer, reject it, or take no position. Before either schedule is filed, preliminary public statements about the offer are filed as SC TO-C, the tender offer equivalent of a Rule 425 communication.

Going private: Schedule 13E-3

If the buyer is an officer, director, major shareholder or another affiliate of the company, taking it private triggers Schedule 13E-3 in addition to whichever proxy or tender offer form the deal structure would otherwise require. Rule 13e-3 exists because an affiliate on both sides of a deal has an obvious conflict of interest, so the schedule requires extra disclosure: whether the transaction is fair to unaffiliated shareholders, how that fairness determination was made, and whether any director disagreed with the board's recommendation.

How many of each form EDGAR actually holds

Pulling a count for each form type from SecFeed's filing index on 2026-11-04 shows the relative frequency of each stage, since EDGAR's index began in the early 1990s:

S-4 and 425 both hit SecFeed's reported count cap of 10,000 (the true totals are higher; the API reports a lower bound past that point rather than counting every row). The order still holds: stock-deal paperwork (S-4, 425) vastly outnumbers going-private filings (SC 13E3), simply because far more deals involve stock consideration or public announcements than involve an affiliate taking a company private.

Pulling M&A filings with the API

SecFeed's M&A Filings API returns this whole set of forms, or any one of them, without you tracking which code maps to which deal stage yourself:

from secfeed import Client

sf = Client("YOUR_API_KEY")
proxies = sf.dataset("mergers-acquisitions", formType="DEFM14A", size=3)
for f in proxies["filings"]:
    print(f["filedAt"], f["companyName"], f["accessionNo"])

A real call against this endpoint on 2026-11-04 returned, among others, a DEFM14A filed the same day by a bank holding company and a DEFM14A filed two days earlier by a cannabis retailer, confirming the feed is current rather than a historical snapshot. Passing ticker instead of formType returns every deal-related form for one company, across every stage from the first Rule 425 communication to the closing 8-K; passing neither returns the whole market's deal activity for a date range. Our guide to SEC filing types covers the full list of EDGAR forms if a filing you're looking at does not appear in the table above, and the full-text search tutorial is the faster path when you only have a company name or a phrase from the agreement, not a form type.

Frequently asked questions

What is the first SEC filing in a merger?

Usually an 8-K under Item 1.01, filed within four business days of signing a definitive merger agreement. Public statements about the deal that come out around the same time, before any proxy or registration statement is ready, are filed separately under Rule 425 or, in a tender offer, Schedule TO-C.

Does every acquisition require a shareholder vote?

No. A cash tender offer made directly to shareholders under Schedule TO does not require a shareholder meeting or vote the way a statutory merger does; shareholders simply decide individually whether to tender their shares. A stock-for-stock merger structured as a statutory merger generally does require a vote, disclosed through a PREM14A and then a DEFM14A.

What is the difference between S-4 and DEFM14A?

An S-4 is a Securities Act registration statement for the new shares an acquirer will issue; a DEFM14A is the definitive proxy statement target shareholders vote on. In a stock-for-stock merger the two are often combined into one joint document, since the target's shareholders are both receiving registered shares and voting on the deal.

Why would a deal file both a tender offer schedule and a 13E-3?

Schedule 13E-3 is not an alternative to the tender offer schedule; it is filed alongside SC TO-T, TO-I or the merger proxy whenever the transaction is a going-private deal involving an affiliate, adding the fairness disclosure Rule 13e-3 requires on top of whatever the deal structure otherwise calls for.