SEPTInvestingStart Free

MTZ SCHEDULE 13D/A: Activist campaign

An amended Schedule 13D was

Filed with the SEC on · accession 0001193125-26-349231

MTZ filed a SCHEDULE 13D/A (schedule 13d/a) with the SEC on Aug 13, 2026. An amended Schedule 13D was filed regarding MasTec Inc., indicating a continued or updated activist/insider ownership position. The stock moved +1.8% by the first close after the filing.

Summary of the filing

An amended Schedule 13D was filed regarding MasTec Inc., indicating a continued or updated activist/insider ownership position. The filing includes an exhibit (PDF) but no specific ownership percentage or stated intent is disclosed in the available text.

For details, click here →

Key details

Subject companyMasTec Inc.

How MTZ stock reacted

Close before

$281.11

Aug 12, 2026

First close after

+1.78%

$286.11

5 trading days

-3.22%

$272.07

Since filing

-38.07%

$174.10

✦ Ask GOAX AI about this filing — what it means for MTZ, what changed since its last filings and what to watch next.

Try it free for 7 days

🔔 Want to stay updated on new SEC filings for MTZ?

Click here

Frequently asked questions

What did MTZ file with the SEC on Aug 13, 2026?

MTZ filed a SCHEDULE 13D/A (Activist campaign). An amended Schedule 13D was filed regarding MasTec Inc., indicating a continued or updated activist/insider ownership position. The filing includes an exhibit (PDF) but no specific ownership percentage or stated intent is disclosed in the available text.

What does a activist campaign mean for MTZ stock?

A settlement removes uncertainty; the stock often reacts to whether the amount is bigger or smaller than investors expected.

How do I read a SCHEDULE 13D/A?

A report the company filed with the SEC (the US market regulator). Start with the summary, then the key amounts and names. Compare it with the company’s earlier filings.

Why are SEC filings important?

Public companies must tell the SEC about anything that can change their value — results, leadership changes, big deals, new shares, bankruptcy. Filings are the official source, often before the news. A SCHEDULE 13D/A (schedule 13d/a): A report the company filed with the SEC (the US market regulator).

How did MTZ stock react to this filing?

MTZ closed at $281.11 before the filing and $286.11 on Aug 13, 2026 (+1.78%). Five trading days later: $272.07 (-3.22%).

Other MTZ SEC filings

Get alerts when MTZ files with the SEC, plus live charts, key levels and news for 13,000+ stocks.

Try SEPT free for 7 days
MTZ overviewMTZ analysisMTZ newsLatest SEC filings