After a strong start on Wednesday morning, mining stocks were in the red by the end of the session as declining manufacturing figures from the world's two largest economies worsened the demand outlook for commodities.The Institute for Supply Management's US manufacturing purchasing managers' index (PMI) fell from 51.3 to 50.7 last month, slightly above forecasts but signalling the slowest rate of expansion so far this year. Meanwhile, the official Chinese manufacturing PMI fell from 50.9 to 50.6 in April, under the 50.7 consensus forecast.Readings above the key 50-point mark point to expansions in activity but both figures pointed to a slowdown from March.Elsewhere, there was an improvement in the UK's own manufacturing PMI which beat expectations with a rise to 49.8 in April, though it still remained in contraction.Copper miner Antofagasta was under the weather despite impressing earlier on with a 12.8% rise in first-quarter production. Analysts at Investec however raised concerns with the stock given the weaker commodity price environment, keeping a 'reduce' rating for the shares. Diversified producer ENRC, which is currently under investigations from the Serious Fraud Office, was a heavy faller on reports that the UK Listings Authority is probing potential breaches of takeover rules. Meanwhile, there were other headlines focusing on issues with the company's flotation in 2007.Fresnillo, Vedanta, Polymetal and EVRAZ were also out of favour this afternoon.Top performing sectors so far todayFixed Line Telecommunications 3,338.34 +2.83%Industrial Transportation 2,664.21 +2.82%Technology Hardware & Equipment 1,189.52 +1.93%Tobacco 39,237.44 +0.77%Food & Drug Retailers 4,598.59 +0.64%Bottom performing sectors so far todayIndustrial Metals & Mining 1,684.89 -2.53%Personal Goods 21,129.97 -1.32%Construction & Materials 3,668.53 -1.29%Electricity 9,741.91 -0.56%Mining 16,210.43 -0.56%BC