Drugs giant GlaxoSmithKline (LON:GSK) has been downgraded to 'underweight' from 'neutral' by City heavyweight JP Morgan Cazenove.
Analysts say they see earnings risk for 2013 as the firm enters an investment phase.
James Gordon noted the group will be launching between six and 12 products over the next three years, which, excluding Relvar, could add £1.9 billion in sales by 2016.
But he said he believed consensus already reflected the topline contribution from these new launches, but not the inevitable costs - for example, for research and development (R&D).
"GSK is entering an investment phase. After reassessing the investment required to execute on the pipeline, already taken for granted by consensus, we now expect operating margins to contract, rather than expand in 2013, and we now forecast a 2013 operating margin 200 bps below consensus," said Gordon.
The analyst has also upped the price target to 1,540 pence, from 1,470 pence previously.
Releasing results last month, the firm said the economic situation in Europe had continued to have a damaging impact on sales in the region.
It said overall turnover was down four per cent in the quarter ended June from the same period last year to £6.5 billion due to poor sales in Europe and the US.