Shares in Whitbread dropped nearly 5% after the company reported slowing sales growth at its Costa coffee chain.
Like-for-like sales at Costa rose 0.6% in the six months to 31 August, while pre-tax profits at the chain slid 10%.
The news overshadowed Whitbread’s near 20% rise in pre-tax profits to £316m, after a good performance from its Premier Inn hotel chain.
Whitbread was the biggest faller on the FTSE 100, with the index up just 1.19 points at 7,525.64 by midday.
Outside the top 100 companies, shares in Carpetright fell 0.8% after the floor coverings and sofa retailer said first-half profits were set to be lower than last year. However, it expects a “significantly” stronger performance in the second half.
Shares in oil services group Hunting jumped 8% after the company said revenues during the past quarter had strengthened, and it now expected full-year revenues to be about $700m (£530m).
On the currency markets, the pound slipped 0.1% against the dollar to $1.3181 and fell 0.2% against the euro to €1.1207.