Gossamer Bio, Inc.
US ˙ NasdaqGS ˙ US38341P1021

SecurityGOSS / Gossamer Bio, Inc.
InstitutionMackenzie Financial Corp
Latest Disclosed Ownership1,536,923 shares
Latest Disclosed Value $ 504,879
Mackenzie Financial Corp reports 401.52% increase in ownership of GOSS / Gossamer Bio, Inc.

On May 13, 2026 - Mackenzie Financial Corp filed a 13F-HR form disclosing ownership of 1,536,923 shares of Gossamer Bio, Inc. (US:GOSS) valued at $504,879 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 18, 2026 disclosing 306,453 shares of Gossamer Bio, Inc.. This represents a change in shares of 401.52% during the quarter. The current value of the position is $273,265 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)
2026-05-13 2026-03-31 13F GOSSAMER BIO COM 38341P102 1,536,923 1,230,470 401.52 505 -47.17 0.0006
2026-02-18 2025-12-31 13F GOSSAMER BIO COM 38341P102 306,453 -2,597 -0.84 954 17.49 0.0011
2025-11-13 2025-09-30 13F GOSSAMER BIO COM 38341P102 309,050 -244,014 -44.12 813 19.41 0.0010
2025-08-13 2025-06-30 13F GOSSAMER BIO COM 38341P102 553,064 200,591 56.91 680 75.71 0.0009
2025-05-07 2025-03-31 13F GOSSAMER BIO COM 38341P102 352,473 52,658 17.56 388 42.80 0.0006
2025-05-02 2024-12-31 13F/A-2 GOSSAMER BIO COM 38341P102 299,815 249,765 499.03 271 453.06 0.0004
2025-02-20 2024-12-31 13F/A-1 GOSSAMER BIO COM 38341P102 299,815 249,765 271 0.0004
2025-02-14 2024-12-31 13F Gossamer Bio Common Stock 38341P102 299,815 249,765 255 0.0004
2024-11-13 2024-09-30 13F GOSSAMER BIO COM 38341P102 50,050 50,050 49 0.0001
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.