NPV of Sierra Mojada is $1.2 Billion pre-tax
If you recall the Preliminary Economic Assessment for Sierra Mojada, see link:
https://silverbullresources.com/news/silver-bull-completes-positive-preliminary-economic-assessment-for-the-sierra-mojada-project-coahuila-mexico/
At Silver $28/oz, Zinc $1.35/lb the PEA would show
NPV = $1.2 Billion
Current Market Cap of SVB = $40 Million
A 10-15% valuation to NPV would mean it goes to $3.50-$5.00.
I think just a long-deserved revaluation is taking place and an appreciation of resource.
Note all of this is only what has been discovered. South32 is around because the geology is the same as Wildcat Silver/Arizona Mining and they have confidence they will find the main ore body. In that case SVB would be worth 10x current found resource. This is an option on silver with no expiration date and a major player who wants to be in their sandbox.