Martin Marietta Materials, Inc.
MX ˙ BMV ˙ US5732841060
SecurityMX:MLM / Martin Marietta Materials, Inc.
InstitutionBlair William & Co/il
Latest Disclosed Ownership43,837 shares
Latest Disclosed Value $ 25,805,769
Blair William & Co/il reports 203.10% increase in ownership of MLM / Martin Marietta Materials, Inc.

On May 8, 2026 - Blair William & Co/il filed a 13F-HR form disclosing ownership of 43,837 shares of Martin Marietta Materials, Inc. (MX:MLM) valued at $25,805,769 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 14,463 shares of Martin Marietta Materials, Inc.. This represents a change in shares of 203.10% during the quarter.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

Upgrade to unlock premium data and export to Excel .

Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-05-08 2026-03-31 13F MARTIN MARIETTA MATLS COM 573284106 43,837 29,374 203.10 25,806 186.56 0.0740
2026-02-17 2025-12-31 13F MARTIN MARIETTA MATLS COM 573284106 14,463 4,696 48.08 9,006 46.30 0.0242
2025-11-12 2025-09-30 13F MARTIN MARIETTA MATLS COM 573284106 9,767 85 0.88 6,156 15.83 0.0164
2025-07-24 2025-06-30 13F MARTIN MARIETTA MATLS COM 573284106 9,682 -38 -0.39 5,315 14.35 0.0148
2025-05-09 2025-03-31 13F MARTIN MARIETTA MATLS COM 573284106 9,720 -625 -6.04 4,647 -13.03 0.0140
2025-02-12 2024-12-31 13F MARTIN MARIETTA MATLS COM 573284106 10,345 136 1.33 5,343 -2.77 0.0155
2024-11-12 2024-09-30 13F MARTIN MARIETTA MATLS COM 573284106 10,209 2,524 32.84 5,495 32.00 0.0161
2024-08-12 2024-06-30 13F MARTIN MARIETTA MATLS COM 573284106 7,685 2 0.03 4,164 -11.73 0.0128
2024-05-09 2024-03-31 13F MARTIN MARIETTA MATLS COM 573284106 7,683 359 4.90 4,717 29.06 0.0148
2024-02-12 2023-12-31 13F MARTIN MARIETTA MATLS COM 573284106 7,324 426 6.18 3,654 29.07 0.0125
2023-11-09 2023-09-30 13F MARTIN MARIETTA MATLS COM 573284106 6,898 -2,794 -28.83 2,831 -36.72 0.0109
2023-08-11 2023-06-30 13F MARTIN MARIETTA MATLS COM 573284106 9,692 182 1.91 4,475 32.52 0.0164
2023-05-12 2023-03-31 13F MARTIN MARIETTA MATLS COM 573284106 9,510 -449 -4.51 3,377 0.33 0.0135
2023-02-10 2022-12-31 13F MARTIN MARIETTA MATLS COM 573284106 9,959 -27 -0.27 3,366 4.63 0.0146
2022-11-09 2022-09-30 13F MARTIN MARIETTA MATLS COM 573284106 9,986 933 10.31 3,216 18.72 0.0148
2022-08-10 2022-06-30 13F MARTIN MARIETTA MATLS COM 573284106 9,053 -279 -2.99 2,709 -24.58 0.0120
2022-05-13 2022-03-31 13F MARTIN MARIETTA MATLS COM 573284106 9,332 -1,055 -10.16 3,592 -21.50 0.0126
2022-02-14 2021-12-31 13F MARTIN MARIETTA MATLS COM 573284106 10,387 703 7.26 4,576 38.29 0.0144
2021-11-12 2021-09-30 13F MARTIN MARIETTA MATLS COM 573284106 9,684 -1,418 -12.77 3,309 -15.28 0.0113
2021-08-12 2021-06-30 13F MARTIN MARIETTA MATLS COM 573284106 11,102 6,839 160.43 3,906 172.77 0.0135
2021-05-13 2021-03-31 13F MARTIN MARIETTA MATLS COM 573284106 4,263 94 2.25 1,432 20.95 0.0054
2021-02-09 2020-12-31 13F MARTIN MARIETTA MATLS COM 573284106 4,169 -153 -3.54 1,184 16.42 0.0043
2020-11-06 2020-09-30 13F MARTIN MARIETTA MATLS COM 573284106 4,322 -158 -3.53 1,017 9.95 0.0043
2020-08-12 2020-06-30 13F MARTIN MARIETTA MATLS COM 573284106 4,480 1 0.02 925 9.08 0.0044
2020-05-11 2020-03-31 13F MARTIN MARIETTA MATLS COM 573284106 4,479 -77 -1.69 848 -33.44 0.0053
2020-02-13 2019-12-31 13F MARTIN MARIETTA MATLS COM 573284106 4,556 4,556 1,274 0.0065
2019-02-14 2018-12-31 13F MARTIN MARIETTA MATLS COM 573284106 0 -2,003 -100.00 0 -100.00
2018-11-13 2018-09-30 13F MARTIN MARIETTA MATLS COM 573284106 2,003 -548 -21.48 364 -36.14 0.0022
2018-08-13 2018-06-30 13F MARTIN MARIETTA MATLS COM 573284106 2,551 331 14.91 570 23.91 0.0039
2018-05-15 2018-03-31 13F MARTIN MARIETTA MATLS COM 573284106 2,220 376 20.39 460 12.75 0.0033
2018-02-14 2017-12-31 13F MARTIN MARIETTA MATLS COM 573284106 1,844 651 54.57 408 65.85 0.0028
2017-11-13 2017-09-30 13F MARTIN MARIETTA MATERIALS COM 573284106 1,193 159 15.38 246 6.96 0.0018
2017-08-04 2017-06-30 13F MARTIN MARIETTA MATERIALS COM 573284106 1,034 1,034 230 0.0017
2016-11-14 2016-09-30 13F MARTIN MARIETTA MATERIALS COM 573284106 0 -1,678 -100.00 0 -100.00
2016-08-08 2016-06-30 13F MARTIN MARIETTA MATERIALS COM 573284106 1,678 1,678 322 0.0030
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.