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Monday, September 14, 2026 Admin

COSA.V ·

Or FOR Dissemination in the United States

Financings

Cosa Announces Upsized C$12 Million

Bought Deal Private Placement

Including Participation by Denison Mines

NOT FOR DISTRIBUTION TO U.S. NEWSWIRE SERVICES OR FOR DISSEMINATION IN THE UNITED STATES

Vancouver, British Columbia – June 4, 2026 – Cosa Resources Corp. (TSX-V: COSA) (OTCQB: COSAF) (FSE: SSKU) (“Cosa”

or the “ Company”) is pleased to announce that , i n connection with its previously announced “bought deal” private

placement (the “Offering”), it has entered into an amended agreement with Velocity Trade Capital Ltd., on behalf of itself

and a syndicate of underwriters to include Haywood Securities Inc. as co -lead underwriter (collectively, the

“Underwriters”) to increase the size of the Offering to: (i) 5,835,000 common shares of the Company (the “ Non-FT

Shares”) at a price of C$0.60 per Non-FT Share, (ii) 3,045,000 Saskatchewan charity flow-through common shares of the

Company (the “Saskatchewan Charity FT Shares”) at a price of C$0.99 per Saskatchewan Charity FT Share, (iii) 4,020,000

national charity flow-through common shares of the Company (the “ National Charity FT Shares” and together with the

Saskatchewan Charity FT Shares, the “ Charity FT Shares ”) at a price of C$0. 87 per National Charity FT Share and (iv)

2,860,000 flow-through common shares of the Company (the “ FT Shares”, and together with the Non -FT Shares and

Charity FT Shares, the “ Offered Securities ”) at a price of C$0. 70 per FT Share, for aggregate gross proceeds to the

Company of C$12,014,950.

Cosa’s largest shareholder, Denison Mines Corp. (TSX: DML, NYSE American: DNN) (“Denison”), has indicated that it will

participate in the Offering pursuant to its pre -emptive and top-up rights under the investor rights agreement between

Denison and Cosa dated January 14, 2025. Denison is a leading Athabasca Basin-focused uranium mining, development,

and exploration company with a market capitalization of over C$4.5 billion. Denison’s current focus is advancing the

development-stage Wheeler River project, which represents one of the largest undeveloped uranium mining projects in

the infrastructure rich eastern portion of the Athabasca Basin.

Each Charity FT Share and FT Share will qualify as a “flow -through share” within the meaning of the Income Tax Act

(Canada), and in respect of the Saskatchewan Charity FT Shares, will qualify as an “eligible flow-through share” as defined

in The Mineral Exploration Tax Credit Regulations, 2014 (Saskatchewan).

The Company intends to use the net proceeds from the sale of Non-FT Shares to fund exploration and development and

for additional working capital purposes. The gross proceeds from the sale of Charity FT Shares and FT Shares will be used

by the Company to incur eligible “Canadian exploration expenses” that qualify as “flow -through critical mineral mining

expenditures” as such terms are defined in the Income Tax Act (Canada) and, in respect of the gross proceeds received

from subscribers of the Saskatchewan Charity FT Shares and FT Shares , to incur “eligible flow -through mining

expenditures” pursuant to The Mineral Ex ploration Tax Credit Regulations, 2014 (Saskatchewan) (collectively, the

“Qualifying Expenditures ”) related to the Company’s uranium projects in the Athabasca Basin, Saskatchewan, on or

before December 31, 2027. All Qualifying Expenditures will be renounced in favour of the subscribers of Charity FT Shares

and FT Shares effective December 31, 2026. In the event that the Company does not renounce on or prior to December

31, 2026 Qualifying Expenditures in amount equal to the gross proceeds of the Charity FT Shares and FT Shares purchased

and/or if the amount of the Qualifying Expenditures is reduced upon assessment or reassessment by the Canada Revenue

Agency, the Company will indemnify each Charity FT Share and FT Share initial subscriber for the additional income taxes

payable by such initial subscriber as a result of the Company’s failure to renounce the Qualifying Expenditures or as a

result of the reduction.

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Subject to compliance with applicable regulatory requirements and in accordance with National Instrument 45 -106 –

Prospectus Exemptions (“NI 45-106”), the FT Shares will be offered by way of the “accredited investor”, “family, friends

and business associates” and “minimum amount investment” exemptions under NI 45 -106 in all of the provinces of

Canada. The FT Shares issuable pursuant to the Offering will be subject to a hold period in Canada ending on the date

that is four months plus one day following the Closing Date under applicable Canadian securities laws. The Non-FT Shares

and Charity FT Shares will be offered pursuant to Section Part 5A.2 of NI 45-106, as amended by Coordinated Blanket

Order 45-935 – Exemptions from Certain Conditions of the Listed Issuer Financing Exemption to purchasers: (i) in respect

of the Saskatchewan Charity FT Shares, in the province of Saskatchewan only ; and (ii) in respect of the National Charity

FT Shares, in each of the provinces Canada (other than the province of Quebec and Saskatchewan); and (iii) in respect of

the Non-FT Shares, in each of the provinces Canada (other than the province of Quebec) . The Underwriters will also be

entitled to offer the Offered Securities for sale or resale in the United States pursuant to available exemptions from the

registration requirements of the United States, and in certain other jurisdictions outside of Canada and the United States

provided it is understood that no prospectus filing or comparable obligation, ongoing reporting requirement or requisite

regulatory or governmental approval arises in such other jurisdictions. The Non-FT Shares and Charity FT Shares issuable

pursuant to the Offering will not be subject to a hold period in Canada, other than any hold periods required by the TSX

Venture Exchange (the “TSXV”).

The Offering is expected to close on or about June 24, 2026 (the “Closing Date”), or such other date as the Company and

the Underwriters may agree, and is subject to certain conditions including, but not limited to, receipt of all necessary

approvals including the approval of the TSXV.

There is an offering document (the “Offering Document”) related to the offering of Non-FT Shares and Charity FT Shares

that can be accessed under the Company’s profile on SEDAR+ at www.sedarplus.ca and the Company ’s website at

www.cosaresources.ca. Prospective investors of Non-FT Shares and Charity FT Shares should read the Offering Document

before making an investment decision.

The Offered Securities described in this news release have not been, nor will they be, registered under the United States

Securities Act of 1933, as amended (the “U.S. Securities Act”), or any United States state securities laws, and may not be

offered or sold, directly or indirectly, within the United States or to, or for the account or benefit of, U.S. persons absent

registration or an exemption from registration requirements. This news release does not constitute an offer for sale of

securities, nor a solicitation for offers to buy any securities in the Uni ted States, not in any other jurisdiction in which

such offer, solicitation or sale would be unlawful. The terms “United States” and “U.S. person” used herein are as defined

in Regulation S under the U.S. Securities Act.

About Cosa Resources Corp.

Cosa Resources is a Canadian uranium exploration company operating in northern Saskatchewan. The portfolio comprises

roughly 237,000 ha across multiple underexplored 100% owned and Cosa -operated joint venture projects in the

Athabasca Basin region, the majority of which reside within or adjacent to established uranium corridors.

In January of 2025, the Company entered a transformative strategic collaboration with Denison (TSX: DML) (NYSE

American: DNN) that has secured access to several additional highly prospective eastern Athabasca uranium exploration

projects. As Cosa’s largest shareholder, Denison gains exposure to Cosa’s potential for exploration success and its pipeline

of uranium projects.

The Company’s primary focus through the remainder of 2026 will be drilling at the Murphy Lake North and Darby projects

in the eastern Athabasca Basin. Drilling at Murphy Lake North will follow up uranium mineralization within an extensive

zone of strong structure and hydrothermal alteration at the Cyclone trend. Drilling at Darby will follow up on intersections

of anomalous geochemistry, structure, and zones of hydrothermal alteration from both winter 2026 drilling and historical

drilling.

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Cosa’s award-winning management team has a track record of success in Saskatchewan. In 2022, members of the Cosa

team were awarded the AME Colin Spence Award for the discovery of the Hurricane uranium deposit. Cosa personnel

led teams or had integral roles in the discovery of Denison’s Gryphon deposit and held key roles in the founding of both

NexGen and IsoEnergy.

Contact

Keith Bodnarchuk, President & CEO

[email protected]

+1 888-899-2672 (COSA)

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX

Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.

Forward-Looking Information

This press release contains "forward-looking information" within the meaning of applicable Canadian securities laws. Any statements

that express or involve discussions with respect to predictions, expectations, beliefs, plans, projections, objectives, assu mptions or

future events or performance (often, but not always, identified by words or phrases such as "believes", "anticipates", "expec ts", "is

expected", "scheduled", "estimates", "pending", "intends", "plans", "forecasts", "targets", or "hopes", or variations of such words and

phrases or statements that certain actions, events or results "may", "could", "would", "will", "should" "might", "will be tak en", or

"occur" and similar expressions) are not statements of historical fact and may be forward -looking statements. Forward-looking

information herein includes, but is not limited to, statements that address activities, events or developments that Cosa expe cts or

anticipates will or may occur in the future including issuance of the Offered Securities and the closing date of the Offering, proposed

use of proceeds of the Offering and the tax treatment of the Charity FT Shares and FT Shares.

Forward-looking statements and forward-looking information relating to any future mineral production, liquidity, enhanced value and

capital markets profile of the Company, future growth potential for the Company and its business, and future exploration pla ns are

based on management’s reasonable assumptions, estimates, expectations, analyses and opinions, which are based on management’s

experience and perception of trends, current conditions and expected developments, and other factors that management believes are

relevant and reasonable in the circumstances, but which may prove to be incorrect. Assumptions have been made regarding, amon g

other things, the price of metals; costs of exploration and development; the estimated costs of development of exploration projects;

the Company’s ability to operate in a safe and effective manner.

These statements reflect the Company’s respective current views with respect to future events and are necessarily based upon a

number of other assumptions and estimates that, while considered reasonable by management, are inherently subject to signific ant

business, economic, competitive, political and social uncertainties and contingencies. Many factors, both known and unknown, could

cause actual results, performance, or achievements to be materially different from the results, performance or achievements that are

or may be expressed or implied by such forward -looking statements or forward -looking information and the Company has made

assumptions and estimates based on or related to many of these factors. Such factors include, without limitation: the future tax

treatment of the Charity FT Shares and FT Shares, competitive risks and the availability of financing; precious metals price volatility;

risks associated with the conduct of the Company's mining activities; regulatory, consent or permitting delays; risks relating to reliance

on the Company's management team and outside contractors; the Company's inability to obtain insurance to cover all risks, on a

commercially reasonable basis or at all; currency fluctuations; risks regarding the failure to generate su fficient cash flow from

operations; risks relating to project financing and equity issuances; risks and unknowns inherent in all mining projects; contests over

title to properties, particularly title to undeveloped properties; laws and regulations governin g the environment, health and safety;

operating or technical difficulties in connection with mining or development activities; employee relations, labour unrest or

unavailability; the Company's interactions with surrounding communities; the speculative nat ure of exploration and development;

stock market volatility; conflicts of interest among certain directors and officers; lack of liquidity for shareholders of th e Company;

litigation risk; and the factors identified in the Company’s public disclosure docum ents. Readers are cautioned against attributing

undue certainty to forward -looking statements or forward -looking information. Although the Company has attempted to identify

important factors that could cause actual results to differ materially, there may b e other factors that cause results not to be

anticipated, estimated or intended. The Company does not intend, and does not assume any obligation, to update these forward -

looking statements or forward-looking information to reflect changes in assumptions or changes in circumstances or any other events

affecting such statements or information, other than as required by applicable law.