Mastec Inc (NYSE: MTZ), an SEC filer in Water, Sewer, Pipeline, Comm & Power Line Construction, closed at $241.00, -4.0%, on 2026-08-28, with a market cap of $20.2B as of 2026-08-27, a trailing P/E of 49.5, a return on equity of 12.9%, a net margin of 2.8% and 3-year sales growth of 13.5%. Institutional ownership, earnings history and filed financials are on the tabs below.
| # | Holder | Shares | Value | % of shares out | Δ QoQ |
|---|---|---|---|---|---|
| 1 | BlackRock, Inc. | 7,309,6097.3M | $2.4B | 9.27% | ADD 3% |
| 2 | PECONIC PARTNERS LLC | 3,578,4313.6M | $1.2B | 4.54% | ADD 124% |
| 3 | VANGUARD CAPITAL MANAGEMENT LLC | 2,804,2952.8M | $902M | 3.55% | NEW† |
| 4 | VANGUARD PORTFOLIO MANAGEMENT LLC | 2,770,0382.8M | $891M | 3.51% | NEW† |
| 5 | Hill City Capital, LP | 2,155,0002.2M | $693M | 2.73% | — |
| 6 | STATE STREET CORP | 1,869,7881.9M | $602M | 2.37% | ADD 2% |
| 7 | VICTORY CAPITAL MANAGEMENT INC | 1,592,5231.6M | $512M | 2.02% | TRIM -40% |
| 8 | LONE PINE CAPITAL LLCtracked | 1,531,0501.5M | $493M | 1.94% | NEW |
| 9 | FIRST TRUST ADVISORS LP | 1,411,5841.4M | $454M | 1.79% | ADD 8% |
| 10 | GEODE CAPITAL MANAGEMENT, LLC | 1,371,9091.4M | $441M | 1.74% | ADD 12% |
† NEW this big is usually a rename.
Ranked by each filer’s own reported value, not shares.
1 holder — The filer reported no value for this line, so it carries no dollar figure and is left out of the percentage and value columns.
| Biggest buyers | Δ shares | Δ value | |
|---|---|---|---|
| VANGUARD CAPITAL MANAGEMENT LLC | +2,804,295 | $902M | OPEN |
| VANGUARD PORTFOLIO MANAGEMENT LLC | +2,770,038 | $891M | OPEN |
| PECONIC PARTNERS LLC | +1,978,431 | $637M | ADD |
| LONE PINE CAPITAL LLC | +1,531,050 | $493M | OPEN |
| CANADA PENSION PLAN INVESTMENT BOARD | +488,849 | $157M | ADD |
| Biggest sellers | Δ shares | Δ value | |
|---|---|---|---|
| VANGUARD GROUP INC | −5,932,754 | $1.9B | CLOSE |
| VICTORY CAPITAL MANAGEMENT INC | −1,044,928 | $336M | TRIM |
| Third Point LLC | −605,000 | $195M | TRIM |
| JACOBS LEVY EQUITY MANAGEMENT, INC | −596,913 | $192M | TRIM |
| NORDEA INVESTMENT MANAGEMENT AB | −416,641 | $134M | TRIM |
Prior quarter split-rebased · 13Fs are long, US-listed only.
| Holder | 2024-Q4 | 2025-Q1 | 2025-Q2 | 2025-Q3 | 2025-Q4 | 2026-Q1 | Latest value |
|---|---|---|---|---|---|---|---|
| BlackRock, Inc. | 7.3M | 7.7M | 8.2M | 7.7M | 7.1M | 7.3M | $2.4B |
| PECONIC PARTNERS LLC | — | — | — | 750K | 1.6M | 3.6M | $1.2B |
| VANGUARD CAPITAL MANAGEMENT LLC | — | — | — | — | — | 2.8M | $902M |
| VANGUARD PORTFOLIO MANAGEMENT LLC | — | — | — | — | — | 2.8M | $891M |
| Hill City Capital, LP | 2.1M | 2.1M | 2.2M | 2.2M | 2.2M | 2.2M | $693M |
| STATE STREET CORP | 1.9M | 1.9M | 1.9M | 1.8M | 1.8M | 1.9M | $602M |
| VICTORY CAPITAL MANAGEMENT INC | 22K | 33K | 10K | 947K | 2.6M | 1.6M | $512M |
| LONE PINE CAPITAL LLCtracked | — | — | — | — | — | 1.5M | $493M |
| FIRST TRUST ADVISORS LP | 588K | 738K | 672K | 1.0M | 1.3M | 1.4M | $454M |
| GEODE CAPITAL MANAGEMENT, LLC | 1.0M | 1.1M | 1.1M | 1.1M | 1.2M | 1.4M | $441M |
Green = added, red = trimmed, grey = held; a dash is a quarter with no 13F on file — a gap, not an exit.
Breaks = no 13F that quarter.
Short interest has its own tab now — open SI →
SEC Form 13F · ~10,250 filers, 10y · long-only, US-listed, filed ≤45d after quarter-end.
“The purpose of this filing to is report the entry by JM Holdings I on August 10, 2026 into an amendment (the "Fourth Amendment") to the previously reported prepaid variable forward sale contract entered into by JM Holdings I with an unaffiliated party (the "2019 Prepaid Forward Contract," and, as amended to date, the "Prepaid Forward Contract"). The Fourth Amendment amends the Floor Price (as defined below) and Cap Price (as defined below) for each Tranche 1 Component (as defined below), which w”
“The purpose of this filing to is report entry by Jose Ramon Mas on August 10, 2026 into an amendment (the "Fourth Amendment") to the previously reported prepaid variable forward sale contract entered into by Jose Ramon Mas with an unaffiliated party (the "JR 2019 Prepaid Forward Contract," and, as amended to date, the "Prepaid Forward Contract"). The Fourth Amendment amends the Floor Price (as defined below) and Cap Price (as defined below) for each Tranche 2 Component (as defined below), which ”
SEC Schedule 13D/G XML · group aggregate.
