Canadian firms Denison Mines and Fission Uranium have terminated their C$483m ($381.9m) merger agreement following opposition from shareholders.
As part of the agreement signed in July, the companies were to combine their businesses in a court-approved plan of arrangement.
At the deadline for submission of proxies, the shareholders of Denison strongly supported the arrangement.
While many of the Fission shareholders voted in favour, the required two-thirds approval was not obtained, Denison said.
The deal was aimed at creating a leading Canadian focused diversified uranium company with an asset portfolio that would have included Fission's 100%-owned Patterson Lake South Project, and Denison's 60%-owned Wheeler River Project in Canada.
At the time, Fission Uranium chairman and CEO Dev Randhawa said: "Denison has a strong, diversified portfolio and, with the Triple R deposit, Fission is bringing the Athabasca Basin's largest undeveloped high-grade resource as well as a successful and award-winning technical and management team."
If successful, the combined company would have been named Denison Energy Corp and had an estimated market value of around C$900m.
Recently, Denison Mines announced that independent proxy advisory firms Institutional Shareholder Services and Glass, Lewis & Co have recommended that shareholders of both companies vote for the plan of arrangement to combine the two companies.