According to Mining News Pro - The estimated cost was initially pegged at $5.3 billion. Oyu Tolgoi is the Vancouver-based company’s only asset.

Turquoise Hill is owned 50.8% by mining giant Rio Tinto. Rio issued a separate statement Tuesday, saying difficult ground conditions could raise the estimated costs of the copper-gold mine’s expansion, and warning the project could be delayed potentially over two years.  

First production is now expected between May 2022 and June 2023.

On a trading day that saw volume reach 49.8 million on the Nasdaq, nearly 10 times the average volume, Turquoise Hill’s value was pushed down to $1.2 billion.

It is an all-time low for the company, whose market capitalization once sat at over $6 billion.