Waterton said Friday in an open letter to the Hudbay board it would put to shareholders a resolution blocking the ailing copper producer until the 2019 annual meeting from approving new material transactions, transactions that were dilutive on a cash-flow-per-share basis or that involved issuing 5% or more of the company's common shares, unless approved by shareholders.

The mining financier slammed the board for its laissez-faire attitude to two recent requests. Waterton said the board bluntly rejected its initial request that the board commit to put any potential near-term acquisitions to a shareholder vote before consummating any such transactions, and a subsequent request to meet with the board to discuss its revitalization would not happen until November.

"This is categorically unacceptable," Waterton said.

Recent media reports suggested that Hudbay executives were engaged in what seemed to be late-stage negotiations to acquire Chilean miner Mantos Copper for as much as C$1 billion. Waterton warned at the time that should Hudbay continue its current course operationally and/or concluded an M&A transaction, it would cause "massive value destruction".

Waterton is concerned the special meeting will give shareholders a "democratic forum" for expressing their views and concerns regarding any value-destructive transaction the board may be planning to consummate without their approval.

The private investor had harsh words for the board, blaming it's failiure "on multiple fronts" for the 49% slide in Hudbay's share price.

"The current board and management are making a mess out of a portfolio of world class assets," Waterton chief investment officer Isser Elishis said.

Waterton manages two funds that together hold 7% of Hudbay's equity.

"Perhaps the board's lack of urgency stems from a misalignment of interests because, collectively, the board owns 0.12% of the issued and outstanding common shares of Hudbay. While value is being destroyed for the real owners of the business, the ‘stewards' remain largely unimpacted."

He suggested Waterton would like to see Hudbay optimise its portfolio.

"The board's failure to issue a clarifying statement to the market to the effect that it is not pursuing an imminent transaction and its failure to engage in a dialogue with Waterton on an urgent basis leads us to believe that Hudbay may be pursuing such a transaction in the furtherance of a destructive empire building exercise or, perhaps more nefariously, in furtherance of a plan by the board to further entrench itself. This must stop and the true owners of the company must be given a voice."

At an intraday low of C$5.65 a share Friday, Hudbay was trading close to its 12-month bottom of $5.44, down from the $12.65 top during this period. Hudbay has a market capitalisation of about $1.48 billion.