아메리칸 타워 코퍼레이션
MX ˙ BMV ˙ US03027X1000
SecurityMX:AMT / American Tower Corporation
InstitutionFactory Mutual Insurance Co
Latest Disclosed Ownership227,700 shares
Latest Disclosed Value $ 39,296,466
Factory Mutual Insurance Co reports 2.61% increase in ownership of AMT / American Tower Corporation

On May 5, 2026 - Factory Mutual Insurance Co filed a 13F-HR form disclosing ownership of 227,700 shares of American Tower Corporation (MX:AMT) valued at $39,296,466 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 23, 2026 disclosing 221,900 shares of American Tower Corporation. This represents a change in shares of 2.61% 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.

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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)
2026-05-05 2026-03-31 13F AMERICAN TOWER COM 03027X100 227,700 5,800 2.61 39,296 0.87 0.4421
2026-01-23 2025-12-31 13F AMERICAN TOWER CORP COM 03027X100 221,900 -5,800 -2.55 38,959 -11.04 0.3950
2025-11-10 2025-09-30 13F AMERICAN TOWER CORP COM 03027X100 227,700 0 0.00 43,791 -12.99 0.4265
2025-08-07 2025-06-30 13F AMERICAN TOWER CORP COM 03027X100 227,700 0 0.00 50,326 1.57 0.5501
2025-04-17 2025-03-31 13F AMERICAN TOWER CORP COM 03027X100 227,700 0 0.00 49,548 18.64 0.5748
2025-01-24 2024-12-31 13F AMERICAN TOWER CORP COM 03027X100 227,700 46,200 25.45 41,762 -1.06 0.4516
2024-10-10 2024-09-30 13F AMERICAN TOWER CORP COM 03027X100 181,500 18,100 11.08 42,210 32.90 0.4366
2024-07-23 2024-06-30 13F AMERICAN TOWER CORP COM 03027X100 163,400 -2,700 -1.63 31,762 -3.22 0.3618
2024-04-12 2024-03-31 13F AMERICAN TOWER CORP COM 03027X100 166,100 -5,700 -3.32 32,820 -11.51 0.3770
2024-01-23 2023-12-31 13F AMERICAN TOWER CORP COM 03027X100 171,800 0 0.00 37,088 31.28 0.4606
2023-11-07 2023-09-30 13F AMERICAN TOWER CORP COM 03027X100 171,800 26,000 17.83 28,253 -0.08 0.3941
2023-07-27 2023-06-30 13F AMERICAN TOWER CORP COM 03027X100 145,800 0 0.00 28,276 -5.09 0.4171
2023-05-08 2023-03-31 13F AMERICAN TOWER CORP COM 03027X100 145,800 -7,700 -5.02 29,793 -8.39 0.4656
2023-02-02 2022-12-31 13F AMERICAN TOWER CORP COM 03027X100 153,500 0 0.00 32,521 -1.33 0.4918
2022-11-04 2022-09-30 13F AMERICAN TOWER CORP COM 03027X100 153,500 -2,600 -1.67 32,957 -17.39 0.5411
2022-08-08 2022-06-30 13F AMERICAN TOWER CORP COM 03027X100 156,100 -6,600 -4.06 39,897 -2.39 0.6540
2022-05-13 2022-03-31 13F AMERICAN TOWER CORP COM 03027X100 162,700 -6,500 -3.84 40,873 0.12 0.5527
2022-02-10 2021-12-31 13F AMERICAN TOWER CORP COM 03027X100 169,200 -38,450 -18.52 40,825 -25.92 0.5894
2021-11-12 2021-09-30 13F AMERICAN TOWER CORP COM 03027X100 207,650 -3,100 -1.47 55,112 -3.20 0.6884
2021-07-14 2021-06-30 13F AMERICAN TOWER CORP COM 03027X100 210,750 -7,488 -3.43 56,933 9.13 0.6963
2021-05-10 2021-03-31 13F AMERICAN TOWER CORP COM 03027X100 218,238 47,638 27.92 52,172 36.24 0.6674
2021-02-17 2020-12-31 13F AMERICAN TOWER CORP COM 03027X100 170,600 -14,700 -7.93 38,294 -14.51 0.5177
2020-10-19 2020-09-30 13F AMERICAN TOWER CORP COM 03027X100 185,300 0 0.00 44,792 -6.50 0.7249
2020-07-13 2020-06-30 13F AMERICAN TOWER CORP COM 03027X100 185,300 -5,800 -3.04 47,907 15.13 0.8216
2020-04-16 2020-03-31 13F AMERICAN TOWER CORP COM 03027X100 191,100 -1,700 -0.88 41,612 -6.09 0.7902
2020-01-28 2019-12-31 13F AMERICAN TOWER CORP COM 03027X100 192,800 0 0.00 44,310 3.93 0.6533
2019-10-22 2019-09-30 13F AMERICAN TOWER CORP COM 03027X100 192,800 -147,000 -43.26 42,634 -38.63 0.6591
2019-07-16 2019-06-30 13F AMERICAN TOWER CORP COM 03027X100 339,800 2,200 0.65 69,472 5.98 0.8306
2019-04-09 2019-03-31 13F AMERICAN TOWER CORP COM 03027X100 337,600 -34,700 -9.32 65,549 11.30 0.7740
2019-01-14 2018-12-31 13F AMERICAN TOWER CORP COM 03027X100 372,300 0 0.00 58,895 8.87 0.7557
2018-10-10 2018-09-30 13F AMERICAN TOWER CORP COM 03027X100 372,300 12,200 3.39 54,095 4.20 0.5615
2018-07-19 2018-06-30 13F AMERICAN TOWER CORP COM 03027X100 360,100 6,300 1.78 51,916 0.96 0.5571
2018-04-05 2018-03-31 13F AMERICAN TOWER CORP COM 03027X100 353,800 0 0.00 51,421 1.87 0.5631
2018-01-16 2017-12-31 13F AMERICAN TOWER CORP COM 03027X100 353,800 0 0.00 50,476 4.38 0.5280
2017-10-11 2017-09-30 13F AMERICAN TOWER CORP COM 03027X100 353,800 -48,000 -11.95 48,357 -9.05 0.5302
2017-07-10 2017-06-30 13F AMERICAN TOWER CORP COM 03027X100 401,800 -24,000 -5.64 53,166 2.73 0.6149
2017-04-21 2017-03-31 13F AMERICAN TOWER CORP COM 03027X100 425,800 0 0.00 51,752 15.15 0.6130
2017-01-19 2016-12-31 13F AMERICAN TOWER CORP COM 03027X100 425,800 55,000 14.83 44,943 6.95 0.5333
2016-10-26 2016-09-30 13F AMERICAN TOWER CORP COM 03027X100 370,800 0 0.00 42,023 -0.25 0.5197
2016-07-12 2016-06-30 13F AMERICAN TOWER CORP COM 03027X100 370,800 0 0.00 42,127 10.98 0.5550
2016-04-27 2016-03-31 13F AMERICAN TOWER CORP COM 03027X100 370,800 6,000 1.64 37,959 7.33 0.4912
2016-01-14 2015-12-31 13F AMERICAN TOWER CORP COM 03027X100 364,800 0 0.00 35,367 10.19 0.4757
2015-10-14 2015-09-30 13F AMERICAN TOWER CORP COM 03027X100 364,800 0 0.00 32,095 -5.69 0.4390
2015-07-21 2015-06-30 13F AMERICAN TOWER CORP COM 03027X100 364,800 0 0.00 34,032 -0.91 0.4445
2015-04-13 2015-03-31 13F AMERICAN TOWER CORP COM 03027X100 364,800 0 0.00 34,345 -4.76 0.4525
2015-01-12 2014-12-31 13F AMERICAN TOWER CORP COM 03027X100 364,800 -55,000 -13.10 36,060 -8.26 0.4860
2014-11-04 2014-09-30 13F AMERICAN TOWER CORP COM 03027X100 419,800 -143,100 -25.42 39,306 -22.40 0.5436
2014-08-12 2014-06-30 13F AMERICAN TOWER CORP COM 03027X100 562,900 -185,000 -24.74 50,650 -17.28 0.6926
2014-05-15 2014-03-31 13F AMERICAN TOWER CORP COM 03027X100 747,900 23,000 3.17 61,231 5.82 0.8864
2014-02-04 2013-12-31 13F AMERICAN TOWER CORP COM 03027X100 724,900 75,000 11.54 57,862 20.10 0.8510
2013-10-16 2013-09-30 13F AMERICAN TOWER CORP COM 03027X100 649,900 -20,000 -2.99 48,177 -1.71 0.7640
2013-07-25 2013-06-30 13F AMERICAN TOWER CORP COM 03027X100 669,900 669,900 49,017 0.8033
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.