Comfort Systems USA, Inc.
MX ˙ BMV ˙ US1999081045
SecurityMX:FIX / Comfort Systems USA, Inc.
InstitutionWestfield Capital Management Co Lp
Latest Disclosed Ownership620,915 shares
Latest Disclosed Value $ 856,235,416
Westfield Capital Management Co Lp reports 7.16% decrease in ownership of FIX / Comfort Systems USA, Inc.

On May 11, 2026 - Westfield Capital Management Co Lp filed a 13F-HR form disclosing ownership of 620,915 shares of Comfort Systems USA, Inc. (MX:FIX) valued at $856,235,416 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 11, 2026 disclosing 668,835 shares of Comfort Systems USA, Inc.. This represents a change in shares of -7.16% 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)
2026-05-11 2026-03-31 13F COMFORT SYS USA COM 199908104 620,915 -47,920 -7.16 856,235 37.17 3.5924
2026-02-11 2025-12-31 13F COMFORT SYS USA COM 199908104 668,835 -164,360 -19.73 624,217 -9.21 2.6004
2025-11-12 2025-09-30 13F COMFORT SYS USA COM 199908104 833,195 -103,217 -11.02 687,536 36.93 2.8848
2025-08-12 2025-06-30 13F COMFORT SYS USA COM 199908104 936,412 46,773 5.26 502,113 75.10 2.1058
2025-05-09 2025-03-31 13F COMFORT SYS USA COM 199908104 889,639 4,512 0.51 286,757 -23.60 1.3954
2025-02-11 2024-12-31 13F COMFORT SYS USA COM 199908104 885,127 176,947 24.99 375,347 35.78 1.6340
2024-11-12 2024-09-30 13F COMFORT SYS USA COM 199908104 708,180 -156,689 -18.12 276,438 5.10 1.2489
2024-08-14 2024-06-30 13F COMFORT SYS USA COM 199908104 864,869 197,833 29.66 263,024 24.11 1.2923
2024-05-10 2024-03-31 13F COMFORT SYS USA COM 199908104 667,036 240,466 56.37 211,924 141.56 1.1126
2024-02-09 2023-12-31 13F COMFORT SYS USA COM 199908104 426,570 426,570 87,733 0.5113
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.