The London market was lower in afternoon trading as sliding mining stocks led by Glencore weighed on the index.
The FTSE 100 Index fell 16 points to 6852.5, after commodities group Glencore posted lower earnings despite adding its turnaround plan to cut debt through asset sales was on track. The FTSE 250 Index lifted 33 points to 18015.5.
Swiss-based miner said earnings in the first six months of its year tumbled 13% to $4.02bn (£3.05bn), with the firm suffering from softer commodity prices and lower production volumes as world trade slows. Shares fell 9.8p to 180p.
IG senior market analyst Chris Beauchamp said: "UK stocks are tending towards the negative, led down by miners after Glencore's disappointing half-year figures."
However, advertising giant WPP was a strong riser after posting a jump in profits in its first half of the year, adding that the UK's Brexit vote will not hamper its plans for growth.
The group, which includes the Ogilvy & Mather and J Walter Thompson agencies, said pre-tax profit in the period jumped 15.8% to £690m ($910m), boosted by an almost 12% lift in sales to £6.5bn. Shares jumped 101p to 1848p.
In afternoon trading the biggest risers on the FTSE 100 Index were WPP (+101p to 1848p), Barratt Developments (+14.8p to 501p), Berkeley Group (+77p to 2726p), Lloyds Banking (+1.5p to 59.1p) and Persimmon (+48p to 1918p).
The biggest fallers on the FTSE 100 Index were Glencore (-9.8p to 180p), Old Mutual (-7.8p to 196.7p), Fresnillo (-42p to 1794p), Mediclinic International (-23p to 1045p) and Randgold Resources (-170p to 7850p).
In afternoon trading the biggest risers on the FTSE 250 Index were OneSavings Bank (+25p to 262.3p), Shawbrook Group (+15.1p to 204.6p), Countrywide (+15.7p to 273.1p), Aldermore Group (+6.2p to 146.5p) and Marshalls (+12.6p to 299.5p).
The biggest fallers on the FTSE 250 Index were Investec (-22.5p to 470p), Acacia Mining (-14.5p to 559p), Centamin (-4.1p to 165.1p), Vedanta Resources (-10.5p to 527p) and Just Eat (-10p to 573.5p).