The company, which supplies tool, equipment and machinery to businesses from 265 branches across the UK, said trading had been “unpredictable” and softer than it expected in August.
As a result, sales growth in the second half is likely to be between eight and 11 per cent, with earnings expected to be “below current market expectations”.
HSS shares have now lost over 60 per cent of their value since the firm floated in February, closing yesterday at 79p.
“This is obviously disappointing,” chief executive Chris Davies said, as the firm reported a loss of £14.1m for the first half, blaming admin expenses.
He added: “Notwithstanding this, we are confident that our strategy is continuing to underpin our market share progress.”