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Tender offers

How a public offer to buy shares is filed and how long it must stay open, with Merck's April 2026 Schedule TO for Terns Pharmaceuticals.

The short answer

A tender offer is a public offer to buy shares from existing holders, at a stated price, for a stated period. Third-party offers (one company offering to buy another) are filed on Schedule TO under Rule 14d-1. Offers by a company for its own shares are issuer tender offers under Rule 13e-4, also filed on Schedule TO. Under Rule 14e-1, the offer generally has to stay open at least twenty business days.

Third-party offers and issuer offers

Regulation 14D applies to tender offers subject to Section 14(d)(1) of the Exchange Act, the usual path when a bidder is offering to buy a class of another company's shares. Rule 13e-4 defines an issuer tender offer as an offer by the company (or an affiliate) for its own equity. Both kinds of offer are described on Schedule TO. The target company in a third-party offer also files a Schedule 14D-9 stating its board's position on the offer. A going-private deal can add Rule 13e-3. Merger filings covers acquisitions that are structured as mergers rather than as tenders.

Rule 14e-1 makes it unlawful, among other things, to hold a tender offer open for less than twenty business days from the date it is first published or sent to security holders, and to change the price or the percentage sought without leaving the offer open at least ten more business days.

An example: Merck and Terns

Merck's Schedule TO filed April 7, 2026 is a third-party offer subject to Rule 14d-1. The subject company is Terns Pharmaceuticals, Inc. A Merck subsidiary offered to buy the shares for $53.00 per share, net to the seller in cash, without interest, on the terms of an Offer to Purchase dated April 7, 2026. The Schedule TO is the cover statement; the Offer to Purchase, filed as an exhibit, is the document that sets out the price, conditions, timing and the bidder's plans.

How to read a Schedule TO

The cover tells you whether the offer is a third-party offer under Rule 14d-1 or an issuer offer under Rule 13e-4, and names the subject company and the bidder.
The Offer to Purchase (or prospectus, in an exchange offer) has the price, the conditions, and the scheduled expiration date. Conditions can include a minimum number of shares tendered, and regulatory approvals.
Amendments on Schedule TO/A update the count of shares tendered and any extension of the deadline. A final amendment reports the results.
Holders decide whether to tender; this page explains the filing, not whether anyone should.

Common questions

What is a tender offer?

A public offer to buy shares from existing holders at a stated price, for a stated period, rather than buying them in the open market one trade at a time.

What is Schedule TO?

The SEC statement used to commence a tender offer, whether a third-party offer under Rule 14d-1 or an issuer offer under Rule 13e-4. The Offer to Purchase is usually an exhibit.

How long must a tender offer stay open?

Generally at least twenty business days from the date it is first published or sent to holders, under Rule 14e-1. A change in price or in the percentage sought usually adds at least ten business days.

What is an issuer tender offer?

An offer by a company, or an affiliate, for the company's own shares. It can be a cash buyback tender or an exchange offer for other securities.

How is a tender offer different from a merger?

In a tender offer, holders choose whether to sell their shares to the bidder. In a merger, the companies combine under a shareholder vote and, if it is approved, the remaining shares are converted on the merger terms.

Disclosures

Editor holdings: The editor holds no position in any company named on this page. As of Nov 11, 2026.
Compensation: Nobody paid for this page. No affiliate links on this page.
Sources: Each company's own SEC filings, linked next to each number.
Last updated: Nov 10, 2026

General education, the same for every reader. Not a recommendation to buy, sell or hold any security, and it doesn't consider your situation.

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