Why Vox Royalty’s Sorby Hills Deal Hinges on Reserve Conversion

Vox Royalty has paid US$13 million for a royalty on a project where, at the time of the deal, only 39% of the mineral resource had been converted to reserves. That gap is not a flaw in the structure. It is the point of it.

The Sorby Hills silver-lead project in Western Australia is already permitted, funded, and under construction, with first concentrate production targeted for the second half of 2027. Operator Boab Metals has been drilling hard through 2026, lifting the reserve base from 13.6 Mt toward 18.3 Mt in the months before the acquisition landed. A further upgrade is expected within weeks to months.

The royalty itself is an uncapped 0.75% net smelter return, which means every additional tonne converted to reserve extends the effective life of the royalty with no ceiling on what Vox ultimately collects.

This piece unpacks what investors are actually buying when they view Vox Royalty through the Sorby Hills lens: the deal structure, the reserve conversion catalyst and what the numbers say about its timing, how the asset fits Vox’s revenue trajectory toward its 2030 target, and the risks that still demand a clear-eyed read before you draw any conclusions.

What Vox actually acquired and how the royalty is structured

Start with the terms, because everything downstream depends on them. Vox Royalty, through its Australian subsidiary, has agreed to buy an uncapped 0.75% net smelter return (NSR) royalty over the entire Sorby Hills deposit for US$13 million in cash, funded from existing cash on hand.

An NSR royalty pays the holder a fixed percentage of gross revenue from a project, calculated after smelting and refining deductions but before the operator’s own costs. In plain terms, Vox gets paid on the project’s top line, not its profit.

NSR royalty structures across different commodities share the same top-line payment mechanic but diverge significantly in how smelting and refining deductions affect the royalty holder’s realised rate, a distinction that is more pronounced in silver-lead concentrate than in gold doré.

The word that matters most here is “uncapped.” Many royalty agreements carry a ceiling: once cumulative payments hit a set figure, the royalty expires. This one has no such limit. As the reserve base grows beyond today’s 18.3 Mt, Vox captures more years of royalty revenue without any upper bound, a structurally different risk-return position to a capped royalty.

One detail worth clarifying: Vox bought this royalty from a private royalty holder, not from Boab Metals. The ASX-listed operator remains the 100% owner of Sorby Hills, and its position does not change. Vox is a passenger on the revenue line, not a partner in the mine.

The deal is not yet complete. It remains subject to approval from Australia’s Foreign Investment Review Board (FIRB), the body that reviews foreign acquisitions of Australian assets. Closing is anticipated in Q4 2026.

The takeaway is that Vox is not taking operating cost risk. As an NSR holder, it is exposed to revenue and to mine life, which is exactly where the next part of the analysis lives.

The reserve conversion story: why 39% today is the catalyst, not a red flag

Follow the numbers in order. The prior ore reserve estimate sat at 13.6 Mt. A July 2026 update lifted it to 15.2 Mt, a 12% increase. Then, in late September 2026, Boab Metals’ ASX announcements reported a further jump to 18.3 Mt at 3.2% lead and 37.3 g/t silver, roughly 20% above the prior figure.

Each step was driven by drilling, not revision. This was new tonnes being proved up, not old tonnes being reclassified.

Now set that reserve against the total resource. Sorby Hills holds a defined mineral resource of 50.6 Mt at 3.0% lead and 34 g/t silver. With 18.3 Mt converted to reserve, roughly a third of the identified resource has moved into the reserve category, consistent with the 39% figure Spencer Cole, President and Chief Investment Officer of Vox Royalty, cited at announcement.

Here is where a reserve differs from a resource, and why it matters. A mineral resource is a concentration of minerals with reasonable prospects for eventual economic extraction. An ore reserve is the portion of that resource proven, through engineering and economic study, to be mineable at a profit. Converting resource to reserve is the work that turns geology into a bankable mine plan.

The JORC Code definitions for mineral resources and ore reserves draw a precise distinction between mineralisation with reasonable prospects for economic extraction and the subset proven, through engineering study, to be mineable at a profit — the threshold that converts geology into a bankable mine plan.

So the question for a Vox investor is not whether the minerals exist. They are already measured. The question is conversion timing, and management has flagged a clear expectation.

Management anticipates a further reserve upgrade from Boab Metals within weeks to months of the acquisition announcement, with conversion drilling already completed across the B, Omega, Norton and Beta deposits.

The mine life implications follow directly. The DFS base case ran 8.5 years. The September 2026 update extended that to 10.5 years. Management’s stated target, once conversion is more complete, is 12 to 15 years, with an optimistic scenario approaching 20 years.

The Sorby Hills project delivery numbers sit behind the royalty structure: a pre-tax NPV of A$1.06 billion, a 97% IRR, and lead production expected to cover the full operating cost base, leaving silver revenue as near-pure margin for both the operator and, through the NSR, for Vox.

For an uncapped royalty holder, every extra year of mine life is an extra year of cash flow. The gap between today’s 10.5 years and management’s 12-15 year target is where a meaningful slice of this acquisition’s value still sits, waiting to be proven.

What Phase IX drilling results tell us about the resource extension trajectory

Phase IX drilling, 47 holes for approximately 5,880 m, was completed in full by September 2026. The intercepts confirmed extensions beyond the current pit designs, which is the detail that shifts the conversion path from exploration hope to identified geology.

That distinction matters for how you weigh the 12-15 year target. It is not a guess about undiscovered ore. It is a projection anchored to mineralisation that has already been hit by the drill bit.

Additional drilling at the Keep zinc target is also underway. That sits outside the core silver-lead reserve story and represents an incremental optionality layer, a possible source of upside that is not yet baked into any mine life figure.

How Sorby Hills fits Vox Royalty’s revenue trajectory and 2030 ambition

Zoom out from the single asset to the portfolio, and Sorby Hills comes into focus as one piece of a larger revenue pattern. Vox’s current-year revenue tells that story.

First-half revenue exceeded US$20 million, but the shape matters. Q1 came in at roughly US$16 million, which Spencer Cole characterised as an outlier driven by elevated gold price volatility rather than a sustainable run-rate. Q2 was around US$6 million, closer to the underlying pace.

Taken together, Vox projects full-year revenue of approximately US$35 million, roughly double the prior year’s US$16.6 million. Revenue splits roughly two-thirds from a streaming offtake component and one-third from the royalty portfolio.

Then there is the destination. In May 2026, management disclosed a 2030 revenue target of US$66 million, close to another doubling from the current-year projection.

The 2030 revenue target stands at US$66 million, roughly double the current-year projection of US$35 million.

Where does Sorby Hills land in that picture? At prevailing prices, the royalty is expected to generate approximately US$2 million annually once in production. In absolute terms, that is modest against a US$66 million target.

The strategic value is not in the dollar figure. It is in anchoring a long-duration silver royalty that starts flowing in 2027, precisely when Vox needs its development-stage assets to begin translating into producing revenue. That transition is what underpins the credibility of the 2030 number.

There is a valuation tension here you should weigh. Vox trades at roughly 10 times revenue, yet management believes the market is ascribing little to no value to its development-stage assets, of which Sorby Hills is the newest. Whether royalties like this one convert to cash on schedule is central to whether that gap closes, and whether the US$66 million target reads as a plan or a promise.

Strategic mineral supply chains have drawn institutional capital toward royalty and streaming vehicles partly because they offer commodity price exposure without balance sheet liability, a structural advantage that becomes more relevant as sovereign governments compete for offtake from projects like Sorby Hills.

Risks that deserve clear-eyed assessment before drawing conclusions

The case across the preceding sections has leaned positive, and the numbers support that lean. But a royalty on a construction-stage project carries specific exposures that deserve naming, not dismissing.

The most immediate is construction and commissioning. Sorby Hills is still being built, and royalty cash flows begin only once Boab Metals reaches steady-state production. Cost overruns, schedule slips, or commissioning hiccups all sit between the deal and the first royalty cheque.

Commodity price sensitivity is the second. Sorby Hills is a dual-commodity asset, silver and lead, and the roughly US$2 million annual royalty figure is calculated at prevailing prices. It moves with the market. J.P. Morgan’s silver forecasts of around US$70/oz average for 2026 and US$63/oz for 2027 offer supportive context, but these are indicative institutional estimates, not guarantees, and should be treated as such.

The FIRB condition is a distinct, deal-level risk. Until that approval clears in Q4 2026, the royalty rights do not vest. This is separate from anything happening at the project itself.

• FIRB and deal closing risk: The acquisition is not complete until FIRB approves, expected Q4 2026.
• Construction and commissioning risk: Cash flows depend on Boab Metals reaching steady-state production.
• Commodity price sensitivity: Revenue moves with silver and lead prices, both of which are volatile.
• Reserve conversion pace risk: The 12-15 year mine life depends on continued conversion drilling delivering.
• Operator dependency risk: Vox has no operational control over construction pace or production decisions.

The NSR structure removes cost risk but leaves duration risk squarely with the operator. Whether Sorby Hills runs for 10.5 years or 15 years is Boab Metals’ call to execute, not Vox’s.

Investing in Vox Royalty through Sorby Hills is partly a judgment on Boab Metals’ ability to execute construction on schedule and convert resource to reserve on the timeline management has projected.

None of this invalidates the thesis. It simply means the case rests as much on Boab Metals’ execution as on the geology, and each risk comes with a milestone you can track.

Three milestones that will tell investors whether this deal delivers what it promises

This acquisition has built-in checkpoints, which is unusual and useful. Rather than waiting until 2030 to form a view, you can watch three observable, time-bound events unfold over the next 12 to 18 months.

1. FIRB clearance and deal close, expected Q4 2026. The royalty rights do not vest until this clears. It is the prerequisite for everything else.
2. The next Boab Metals reserve upgrade, expected late 2026 to early 2027. This is the most analytically significant milestone. Watch whether it moves mine life from 10.5 years toward 12 years or beyond.
3. First concentrate production, targeted H2 2027. This converts Sorby Hills from a development-stage asset to a producing royalty, which changes how the market values the exposure.

The reserve upgrade is the one to weight most heavily. The degree to which it pushes mine life higher is the first real-world test of whether the uncapped royalty was worth US$13 million, and it arrives within months, not years.

For an investor who finds the structure compelling but wants evidence before committing, these three events form a natural observation schedule that begins in late 2026.

This article is for informational purposes only and should not be considered financial advice. Investors should conduct their own research and consult with financial professionals before making investment decisions. Past performance does not guarantee future results. Financial projections are subject to market conditions and various risk factors. These statements are speculative and subject to change based on market developments and company performance.