The London market drifted lower in afternoon trading on Thursday (25 August 2016) after US Presidential candidate Hillary Clinton vowed to pressure drug firms to lower prices. Clinton said she would "take on" pharmaceutical companies that charge Americans the highest prices in the world for drugs developed in part with government funds.

She told a Cleveland audience: "Your tax dollars helped support the research that is used to create those drugs in the first place."

The FTSE 100 Index fell by 15.9 points to 6820, after pharmaceutical shares declined on the possibility of seeing lower revenues from the US – the world's biggest medical market. The FTSE 250 Index was down 166.6 points to 17848.1.

Hikma Pharmaceuticals was 99p lower at 2129p, while Shire fell 182p to 4843p, in an August market that typically sees lighter investor activity.

IG chief market analyst Chris Beauchamp said: "Thinner volumes continue to amplify the moves, giving them a greater impression of weight than they deserve."

In afternoon trading the biggest risers on the FTSE 100 Index were CRH (+98p to 2567p), Marks & Spencer (+8.6p to 346.6p), Imperial Brands (+53.5p to 4059.5p), United Utilities (+12.5p to 981.5p) and Severn Trent (+29p to 2422p).

The biggest fallers on the FTSE 100 Index were Hikma Pharmaceuticals (-99p to 2129p), Glencore (-7p to 177.1p), Shire (-182p to 4843p), Taylor Wimpey (-5.5p to 163p) and Dixons Carphone (-12.5p to 374.5p).

In afternoon trading the biggest risers on the FTSE 250 Index were Shawbrook (+16.6p to 221p), Aldermore Group (+10p to 157p), John Laing (+11.2p to 247.5p), OneSavings Bank (+11p to 288.3p) and Playtech (+35p to 934.5p).

The biggest fallers on the FTSE 250 Index Entertainment One (-40.8p to 210p), Hochschild Mining (-21.8p to 262.2p), Allied Minds (-22.4p to 386.6p), Just Eat (-28p to 541p) and Carillion (-12.6p to 283.6p).