Growth concerns hammered markets across the globe on Thursday, with banking and mining stocks bearing the brunt of the sell-off in London as the impressive year-to-date rally ran out of steam.As such, there were no sectors in the UK in positive territory by the afternoon, with every category either flat or in the red.Cyclical sectors, such as financials and resources, tend to perform well when the outlook for the global economy improves. Therefore, it was no surprise that they were under heavy selling pressure today given worries about how a potential tapering of stimulus in the US and a slowdown in China - the world's two-largest economies - could affect demand.Answering questions in Congress last night was Federal Reserve Chairman Ben Bernanke who seemed to U-turn on earlier comments by hinting that the central bank could begin to scale back quantitative easing "in the next few meetings" if there is a sustained improvement in the economy.Given that global central-bank stimulus had a big part to play in the near-16% jump on the FTSE 100 since the start of 2013 (as of yesterday's close), there are concerns that a premature tapering could de-rail the economic recovery and see share prices begin to reverse.These concerns were compounded on Thursday as better-than-expected US labour-market data - jobless claims came in lower than forecast - prompted an adverse reaction on equity indices given that it throws more weight behind the argument to 'taper'.Meanwhile, factory activity growth in China moved backed into negative territory in May, with the manufacturing purchasing managers' index unexpectedly falling to a seven-month low of 49.6 from the previous 50.4.Asia-focused banking group Standard Chartered was among the worst performers of the day on the FTSE 100, falling 5.2% in afternoon trade, following closely behind by sector peers Barclays, RBS and Lloyds.Meanwhile, demand concerns weighed heavily on the share prices of Anglo American, Antofagasta and Glencore Xstrata.Top performing sectors so far todayBottom performing sectors so far todayIndustrial Metals & Mining 1,661.85 -6.37%Technology Hardware & Equipment 1,150.83 -5.72%Automobiles & Parts 6,948.73 -4.71%Mining 16,804.31 -4.16%Banks 5,099.50 -4.03%