UK stocks erased early gains as Greek concerns and a lack of economic data stoked investor uncertainty. Sector-wise, financials delivered the biggest drag, while energy stocks and miners provided a welcome boost.As of 13:30, the FTSE 100 was trading flat, just 1 point higher at 6,961 points.Fresnillo topped the risers after declaring that it remains on track to hit its output guidance in 2015, following a strong start to the year.Sector peer Rio Tinto surged after making headlines on rumours it could raise $1bn from the sale of some aluminum assets. Miners were broadly rebounding from Friday's losses, including Randgold Resources, Glencore and Antofagasta.However, BHP Billiton was trading with heavy losses after its South32 spin-off was valued at the lower end of market expectations on its debut on the Australian Stock Exchange.Babcock, which employs across defence, energy and transport, gained after posting a 47% rise in pre-tax profit for the year ended March 31st to £313.1m on revenues up 37% at £4.5bn.Shares in industrial engineer Weir Group were advancing after analysts at Citigroup lifted their rating on the stock from 'neutral' to 'buy' and hiked their target price from 1,750p to 2,200p. Lloyds fell after being hit with a downgrade by Investec to 'sell' after the stock recently reached a 6.5-year high. The broker said that the share price is now more than up with events.Other financials were in the red, including Aviva, St James's Place, London Stock Exchange and Aberdeen. RisersFresnillo (FRES) 780.00p +3.72%Sage Group (SGE) 561.00p +3.12%Royal Mail (RMG) 499.90p +2.99%Babcock International Group (BAB) 1,109.00p +2.59%Marks & Spencer Group (MKS) 580.00p +2.11%Weir Group (WEIR) 1,937.00p +2.05%Randgold Resources Ltd. (RRS) 4,940.00p +1.48%Glencore (GLEN) 297.15p +1.31%Taylor Wimpey (TW.) 187.00p +1.25%GKN (GKN) 357.90p +1.16%FallersBHP Billiton (BLT) 1,468.00p -4.24%Aviva (AV.) 532.50p -1.84%Hikma Pharmaceuticals (HIK) 2,064.00p -1.76%Lloyds Banking Group (LLOY) 88.07p -1.04%St James's Place (STJ) 934.50p -1.01%Rolls-Royce Holdings (RR.) 1,003.00p -0.99%Imperial Tobacco Group (IMT) 3,209.00p -0.90%easyJet (EZJ) 1,685.00p -0.88%Associated British Foods (ABF) 2,886.00p -0.79%Anglo American (AAL) 1,082.00p -0.78%