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Merger and acquisition filings
The 8-Ks, S-4 and proxy statement that follow a deal from signing to closing, with Synopsys's acquisition of Ansys.
The short answer
A large acquisition leaves a trail of SEC filings. The buyer and target each file an 8-K under Item 1.01 when they sign the merger agreement. If the buyer pays partly in its own shares, it registers them on Form S-4, which doubles as the proxy statement for the target's shareholder vote. When the deal closes, the buyer files an 8-K under Item 2.01, and later adds the target's financial statements.
The filings, in order
| Stage | Filing | What it says |
|---|---|---|
| Signing | 8-K, Item 1.01 (often with 7.01 or 8.01) | The merger agreement: price, form of payment, conditions and break fees. The agreement itself is usually attached. |
| Announcement materials | Rule 425 or DEFA14A filings | Press releases, investor slides and call transcripts about the deal. |
| Registration and vote | Form S-4 (a combined proxy statement and prospectus) or a merger proxy, DEFM14A | Background of the deal, the bankers' fairness opinions, projections, risks and the vote date. |
| Vote results | 8-K, Item 5.07 | How the target's shareholders voted. |
| Closing | 8-K, Item 2.01 (often with 2.03 for new debt and 5.02 for board changes) | The deal is done, and the final terms. |
| Afterwards | 8-K/A, Item 9.01 | The target's financial statements and pro forma combined figures, when the deal is big enough. |
A cash tender offer, the other common route, uses Schedule TO from the buyer and Schedule 14D-9 from the target instead of a shareholder vote.
An example: Synopsys and Ansys
Synopsys signed its agreement to buy Ansys on Jan 15, 2024, and reported it the next day in an 8-K under Item 1.01. Each Ansys share was to receive 0.3450 of a Synopsys share plus $197.00 in cash. Because part of the price was paid in Synopsys stock, Synopsys registered those shares on a Form S-4 in March 2024, which also served as Ansys's proxy statement for its shareholder vote.
The deal closed on Jul 17, 2025, 549 days after signing, after review by competition regulators in several countries. The 8-K under Item 2.01 shows the final terms changed slightly: each Ansys share received 0.3399 of a Synopsys share and $199.91 in cash. The agreement capped the new Synopsys shares at just under 20% of those outstanding (stock exchange rules generally require a vote by the buyer's own shareholders above 20%), so the exchange ratio was cut to fit and the cash was raised to make up the difference.
What to read closely
- Conditions to closing: regulatory approvals, shareholder votes and financing. They explain most of the time between signing and closing.
- Termination fees: what one side pays the other if the deal falls apart for specified reasons.
- Background of the merger in the S-4 or proxy: a dated account of the talks, other bidders and how the price was reached.
- After closing: the buyer's next 10-Q or 10-K shows how the price was split between identifiable assets and goodwill.
Common questions
Which 8-K item reports a merger agreement?
Item 1.01, entry into a material definitive agreement. The closing is reported under Item 2.01, completion of acquisition or disposition of assets.
What is a Form S-4?
A registration statement for shares a company issues in a merger or exchange offer. It usually doubles as the proxy statement for the shareholder vote.
What is a DEFM14A?
A definitive proxy statement for a merger vote, filed when the target's shareholders vote but no new shares need registering, as in an all-cash deal.
Why can merger terms change between signing and closing?
The agreement can include adjustments, as in Synopsys's purchase of Ansys, where a cap on new shares lowered the exchange ratio and raised the cash per share.
How long does a large acquisition take to close?
It varies with regulatory review. Synopsys's acquisition of Ansys took 549 days from signing to closing.
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 9, 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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