Johannesburg - Impala Platinum reported a 47% surge in quarterly output on Thursday, recovering from a low base caused by an unprecedented five-month strike last year.
Implats said production came in at 310 000 ounces in the three months to the end of March compared with 273 000 in the same period a year earlier.
However output has failed to fully recover so far this financial year, which ends on June 30, and is down 6% at 932 000 ounces, sending shares in the company nearly 4% lower.
By 14:54 GMT, the stock was down 3.62% to R64.52, lagging behind a flat JSE Top-40 index.
"It looks like the company is struggling to ramp up production after the strike last year and the market doesn't like that," one London-based analyst said.
Implats [JSE:IMP], along with rivals Lonmin [JSE:LON] and Anglo American Platinum [JSE:AMS], is still recovering from last year's strike that cost the industry billions of dollars in lost output and damaged the viability of some mines and led to job cuts.
The strike and depressed prices of the metals used in auto catalysts prompted a strategic review in the sector that has included selling underperforming mines and scaling back on capital expenditure.
Platinum has lost about 20% in the last year alone and its recovery prospects have been tarnished by large stocks, increased recycling and slower demand growth from the automotive industry.
Implats also warned that output could be severely affected if Eskom imposes more frequent blackouts.