Definition
A third-party tender offer is a tender offer launched by a party other than the company whose shares are being bought. The party making the offer is the bidder (or offeror); the company whose shares are sought is the target.
Why it matters
Third-party tender offers are the dominant structure in public-company M&A: an acquirer offers a per-share price to all shareholders for some or all of the company’s stock. In the private-company context, a third-party tender offer typically takes the form of an outside investor (or syndicate) buying secondary shares at a uniform price from a defined eligible-seller pool.
Regulatory frame
In the U.S., third-party tender offers are subject to Regulation 14D and Regulation 14E, including required filings on Schedule TO, mandatory minimum offer windows, withdrawal rights, the all-holders / best-price rule, and (where the bidder crosses 5% beneficial ownership) Schedule 13D disclosure.
Distinction from issuer tender
If the buyer is the issuer itself, the transaction is an issuer tender offer governed by Rule 13e-4 with stricter disclosure.