British online supermarket and technology firm Ocado said on Wednesday that CEO Tim Steiner will temporarily lead Ocado Solutions, the company's sub-unit which focuses on an all-encompassing technology platform for retailers. The move comes as John Martin, the current boss of Ocado Solutions, steps down after 18 months in the role, the company said in a statement. Ocado shares fell 6.9 per cent to 291.6 pence by 1446 GMT on the London bourse, while the broader mid-cap FTSE-250 index was down 0.