
GlaxoSmithKline's shares are still up 7% following the tie-up announced with Pfizer.
The company has said that the deal will save costs and this looks likely to have an impact on staff.
Emma Walmsley, chief executive of Glaxo, said: "Obviously there's going to be some impact on people. That's something we are working through and we will certainly be talking to our employees before we start talking about that in any way publicly."