American Tower Corporation
US ˙ NYSE ˙ US03027X1000

SecurityAMT / American Tower Corporation
InstitutionAssetmark, Inc
Latest Disclosed Ownership121,090 shares
Latest Disclosed Value $ 20,897,662
Assetmark, Inc reports 36.33% increase in ownership of AMT / American Tower Corporation

On May 6, 2026 - Assetmark, Inc filed a 13F-HR form disclosing ownership of 121,090 shares of American Tower Corporation (US:AMT) valued at $20,897,712 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 23, 2026 disclosing 88,821 shares of American Tower Corporation. This represents a change in shares of 36.33% during the quarter. The current value of the position is $22,067,442 USD.

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)
2026-05-06 2026-03-31 13F AMERICAN TOWER COM 03027X100 121,090 32,269 36.33 20,898 34.01 0.0426
2026-01-23 2025-12-31 13F AMERICAN TOWER CORP COM 03027X100 88,821 -4,093 -4.41 15,594 -12.73 0.0318
2025-11-06 2025-09-30 13F AMERICAN TOWER CORP COM 03027X100 92,914 17,147 22.63 17,869 6.71 0.0383
2025-08-04 2025-06-30 13F AMERICAN TOWER CORP COM 03027X100 75,767 55,982 282.95 16,746 288.97 0.0395
2025-05-06 2025-03-31 13F AMERICAN TOWER CORP COM 03027X100 19,785 5,015 33.95 4,305 58.97 0.0118
2025-02-06 2024-12-31 13F AMERICAN TOWER CORP COM 03027X100 14,770 12,406 524.79 2,709 393.26 0.0074
2024-11-01 2024-09-30 13F AMERICAN TOWER CORP COM 03027X100 2,364 1,641 226.97 550 292.14 0.0016
2024-08-13 2024-06-30 13F AMERICAN TOWER CORP COM 03027X100 723 -8,666 -92.30 141 -92.45 0.0004
2024-05-07 2024-03-31 13F AMERICAN TOWER CORP COM 03027X100 9,389 -425 -4.33 1,855 -12.42 0.0060
2024-02-09 2023-12-31 13F AMERICAN TOWER CORP COM 03027X100 9,814 2,196 28.83 2,119 69.17 0.0077
2023-10-27 2023-09-30 13F AMERICAN TOWER CORP COM 03027X100 7,618 -3,038 -28.51 1,253 -39.40 0.0050
2023-08-11 2023-06-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 10,656 269 2.59 2,067 -2.64 0.0081
2023-05-05 2023-03-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 10,387 1,637 18.71 2,122 14.52 0.0088
2023-02-10 2022-12-31 13F AMERICAN TOWER CORP COM 03027X100 8,750 2,772 46.37 1,854 44.43 0.0080
2022-11-01 2022-09-30 13F AMERICAN TOWER CORP COM 03027X100 5,978 241 4.20 1,283 -12.48 0.0060
2022-08-03 2022-06-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 5,737 1,869 48.32 1,466 50.82 0.0066
2022-05-13 2022-03-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 3,868 610 18.72 972 1.99 0.0041
2022-02-14 2021-12-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 3,258 1,381 73.57 953 91.37 0.0039
2021-11-12 2021-09-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 1,877 -279 -12.94 498 -14.43 0.0022
2021-08-16 2021-06-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 2,156 -222 -9.34 582 2.46 0.0027
2021-05-14 2021-03-31 13F AMERICAN TOWER CORP COM 03027X100 2,378 -1,276 -34.92 568 -30.73 0.0029
2021-02-10 2020-12-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 3,654 -2,922 -44.43 820 -48.43 0.0046
2020-11-13 2020-09-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 6,576 207 3.25 1,590 -3.46 0.0103
2020-08-11 2020-06-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 6,369 -8,443 -57.00 1,647 -48.93 0.0118
2020-05-12 2020-03-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 14,812 5,239 54.73 3,225 46.59 0.0273
2020-02-11 2019-12-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 9,573 4,462 87.30 2,200 94.69 0.0167
2019-11-13 2019-09-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 5,111 255 5.25 1,130 13.80 0.0095
2019-08-14 2019-06-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 4,856 1,686 53.19 993 58.88 0.0081
2019-05-14 2019-03-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 3,170 38 1.21 625 26.26 0.0056
2019-02-13 2018-12-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 3,132 -139 -4.25 495 4.21 0.0048
2018-11-13 2018-09-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 3,271 224 7.35 475 8.20 0.0043
2018-08-01 2018-06-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 3,047 -179 -5.55 439 -6.40 0.0043
2018-05-16 2018-03-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 3,226 164 5.36 469 7.32 0.0049
2018-02-13 2017-12-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 3,062 -11,144 -78.45 437 -77.50 0.0045
2017-11-08 2017-09-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 14,206 -60,156 -80.90 1,942 -80.26 0.0221
2017-08-14 2017-06-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 74,362 3,264 4.59 9,839 13.86 0.1238
2017-09-15 2017-03-31 13F/A-1 AMERICAN TOWER CORP NEW COM COM 03027X100 71,098 6,605 10.24 8,641 26.78 0.1135
2017-05-08 2017-03-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 71,098 6,605 8,641
2017-09-15 2016-12-31 13F/A-1 AMERICAN TOWER CORP NEW COM COM 03027X100 64,493 6,663 11.52 6,816 4.00 0.1001
2017-02-14 2016-12-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 64,493 6,663 6,816
2017-09-14 2016-09-30 13F/A-1 AMERICAN TOWER CORP NEW COM COM 03027X100 57,830 57,266 10,153.55 6,554 10,140.63 0.0997
2016-11-04 2016-09-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 57,830 57,266 6,554
2017-09-14 2016-06-30 13F/A-1 AMERICAN TOWER CORP NEW COM COM 03027X100 564 -107 -15.95 64 -7.25 0.0011
2016-08-08 2016-06-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 564 -107 64
2017-09-14 2016-03-31 13F/A-1 AMERICAN TOWER CORP NEW COM COM 03027X100 671 163 32.09 69 40.82 0.0012
2016-05-13 2016-03-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 671 163 69
2017-09-14 2015-12-31 13F/A-1 AMERICAN TOWER CORP NEW COM COM 03027X100 508 223 78.25 49 96.00 0.0009
2016-02-12 2015-12-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 508 223 49
2016-01-05 2015-09-30 13F/A-1 AMERICAN TOWER CORP NEW COM COM 03027X100 285 -14,760 -98.11 25 -98.22 0.0005
2015-11-10 2015-09-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 285 25
2015-08-13 2015-06-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 15,045 1,517 11.21 1,404 10.20 0.0292
2015-05-12 2015-03-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 13,528 13,528 -10.08 1,274 -9.26 0.0271
2015-02-03 2014-12-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 0 -11,217 -100.00 0 -100.00
2014-11-10 2014-09-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 11,217 333 3.06 1,050 7.25 0.0243
2014-08-12 2014-06-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 10,884 -5,943 -35.32 979 -28.96 0.0209
2014-05-06 2014-03-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 16,827 -2,500 -12.94 1,378 -10.69 0.0336
2014-02-11 2013-12-31 13F AMERICAN TOWER CORP NEW COM COM 03027X100 19,327 -985 -4.85 1,543 2.46 0.0365
2014-02-11 2013-09-30 13F/A-1 AMERICAN TOWER CORP NEW COM COM 03027X100 20,312 20,312 1,506 0.0380
2013-11-14 2013-09-30 13F AMERICAN TOWER CORP NEW COM COM 03027X100 20,312 1,506 0.0380
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.