(Sharecast News) - London's FTSE 100 was flat at 9,701.85 in afternoon trade on Wednesday

Miners Glencore, Antofagasta, Anglo American and Rio Tinto were among the top performers as copper prices rose.

Housebuilder Berkeley Group also gained after an upgrade to 'buy' at Jefferies. The bank cited impending changes in London housing policy which it sees offering significant upside potential in profitability in the medium term.

Sainsbury's slumped after JPMorgan Securities said after the close on Tuesday that the Qatar Investment Authority was planning to sell up to 97.5m shares in the supermarket chain.

QIA had been Sainsbury's largest shareholder, with a stake of 10.5%.

Dan Coatsworth, head of markets at AJ Bell, said: "The stock has enjoyed a good run since April, thanks to business progress. A food-first strategy has reaped significant rewards and Sainsbury's has managed to breathe new life into the business.

"QIA might take the view that now is a good time to cut its exposure as Sainsbury's regaining its mojo is one thing, taking it to another level is more challenging.

"Competition in the grocery sector is fierce. Aldi and Lidl are showing no signs of taking their foot off the pedal, rival Asda is working hard to play catch-up after a lacklustre few years, and Tesco continues to dominate. Sainsbury's might find it hard to further increase its market share unless one of its rivals makes a serious mistake."

Barratt Redrow lost ground as Jefferies downgraded the shares to 'hold', noting it sees better risk/reward elsewhere in the sector.

FTSE 100 - Risers

Glencore (GLEN) 381.05p 5.74%

Antofagasta (ANTO) 2,906.00p 4.87%

Diageo (DGE) 1,764.00p 2.29%

Berkeley Group Holdings (The) (BKG) 3,670.00p 2.23%

Anglo American (AAL) 2,918.00p 2.17%

Informa (INF) 952.80p 1.66%

GSK (GSK) 1,846.50p 1.51%

Rio Tinto (RIO) 5,498.00p 1.50%

Imperial Brands (IMB) 3,303.00p 1.32%

Kingfisher (KGF) 313.10p 1.29%

FTSE 100 - Fallers

Sainsbury (J) (SBRY) 313.00p -3.99%

Metlen Energy & Metals (MTLN) 42.65p -3.72%

ICG (ICG) 1,998.00p -2.35%

St James's Place (STJ) 1,333.50p -2.02%

Beazley (BEZ) 768.00p -1.98%

Convatec Group (CTEC) 228.00p -1.72%

Flutter Entertainment (DI) (FLTR) 15,690.00p -1.69%

NATWEST GROUP (NWG) 630.00p -1.59%

Marks & Spencer Group (MKS) 335.60p -1.32%

Barratt Redrow (BTRW) 376.80p -1.31%