Marten Transport, Ltd.
US ˙ NasdaqGS ˙ US5730751089

SecurityMRTN / Marten Transport, Ltd.
InstitutionBoston Partners
Latest Disclosed Ownership1,699,815 shares
Latest Disclosed Value $ 22,322,776
Boston Partners reports 84.85% increase in ownership of MRTN / Marten Transport, Ltd.

On May 11, 2026 - Boston Partners filed a 13F-HR form disclosing ownership of 1,699,815 shares of Marten Transport, Ltd. (US:MRTN) valued at $22,318,571 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 919,562 shares of Marten Transport, Ltd.. This represents a change in shares of 84.85% during the quarter. The current value of the position is $29,780,759 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)
2026-05-11 2026-03-31 13F MARTEN TRANS COM 573075108 1,699,815 780,253 84.85 22,323 113.28 0.0100
2026-02-13 2025-12-31 13F MARTEN TRANS COM 573075108 919,562 919,562 10,466 0.0108
2023-02-08 2022-12-31 13F MARTEN TRANS COM 573075108 0 -21,088 -100.00 0 -100.00
2022-11-09 2022-09-30 13F MARTEN TRANS COM 573075108 21,088 -7,158 -25.34 404 -14.95 0.0006
2022-08-10 2022-06-30 13F MARTEN TRANS COM 573075108 28,246 4,200 17.47 475 11.24 0.0007
2022-05-10 2022-03-31 13F MARTEN TRANS COM 573075108 24,046 -4,458 -15.64 427 -12.68 0.0005
2022-02-04 2021-12-31 13F MARTEN TRANS COM 573075108 28,504 -23,211 -44.88 489 -39.70 0.0006
2021-11-05 2021-09-30 13F MARTEN TRANS COM 573075108 51,715 -8,087 -13.52 811 -17.83 0.0010
2021-08-12 2021-06-30 13F MARTEN TRANS COM 573075108 59,802 -19,190 -24.29 987 -26.40 0.0013
2021-05-10 2021-03-31 13F MARTEN TRANS COM 573075108 78,992 78,992 1,341 0.0018
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.