Sibanye Stillwater Balances Siphumelele Momentum Against US Platinum Recovery

Sibanye Stillwater's mechanised Siphumelele UG2 project is advancing on two separate tracks, and the gap between them tells much about where the company's South African development story stands. The first phase has moved into execution, while the second remains stuck at the pre-feasibility stage. According to Mining Weekly, a possible extension to 1,200 metres is now under review for that second phase.

Development work on phase one got underway in the third quarter of 2026, and Sibanye said on 5 November that the expansion was running to schedule at the South African site. That the two phases sit at such different points — one already being built, the other still being tested on paper — is the detail worth watching. For the first, the reported on-schedule progress is the yardstick as long as execution holds. For the second, the verdict depends on how the next round of project review turns out.

Siphumelele points to the broader shift toward mechanised mining, and what matters for investors is the practical delivery rather than the label. Mechanisation on its own offers little to go on; a development step that has actually begun and is tracking its plan is the more tangible signal. The project deserves attention on that basis, though it does not carry the whole investment case by itself.

US platinum operation still feeling strike fallout

The operational backdrop that has to support that project view looks far less comfortable in the US. After a strike of roughly five weeks, platinum output there fell 19% year on year in the third quarter, while production costs climbed 39% to US$1,617 per ounce. The workforce stood about a quarter below planned levels once the stoppage ended, leaving the company focused on rebuilding both headcount and output. Whether that recovery genuinely takes hold is what counts for any assessment of the business.

At group level the picture was brighter. Adjusted EBITDA rose 9% year on year in the third quarter of 2026 to R10.8 billion. Sibanye also held to its production targets for 2026 across the South African operations, which the company said were on plan, with forecasts outside the US platinum business staying on course.

The US division is a different matter. Following the strike, Sibanye cut its 2026 production guidance for US platinum to between 245,000 and 255,000 ounces, and lifted its expected all-in sustaining costs to a range of US$1,700 to US$1,760 per ounce. The company attributed both revisions to the strike.

Two measures, one investment case

Project development and operational stability are the two connected tests that frame the stock. Siphumelele offers a positive signal on the first. It gains weight only if the rebuilding of the US operation keeps pace — and that pairing will decide how convincingly Sibanye brings its longer-term development ambitions together with the day-to-day running of its mines.