The utilities industry was the only sector trading in positive territory on Thursday as investors turned to defensive assets amid a wider market sell-off.London's FTSE 100 was trading as much as 1% lower during today's session as investors scaled back their risk appetite ahead of a potential tapering of stimulus by the Federal Reserve next week.Defensive stocks are often seen as safer investments in times of volatility, given that they have relatively stable earnings regardless of the state of the overall equity market.Alexander Young, Senior Sales Trader at CMC Markets, said that the prospect of a taper at the Fed's meeting on December 17-18th is "becoming more real by the day" and this has "created sufficient uncertainty amongst traders to take some risk off the table".United Utilities was among the best performers on the FTSE 100, rising 1.6% to 654.5p, while National Grid added 1.3% to 755.5p.Pennon, Centrica and Severn Trent were also in demand.The sector was also benefitting from analysts' comments today after JPMorgan Chase & Co eased fears about the near-term credit impact from UK regulation and Standard & Poor's said that regulatory changes would benefit water, electricity and gas providers.Top performing sectors so far todayGas, Water & Multiutilities 5,407.09 +0.73%Bottom performing sectors so far todayOil Equipment, Services & Distribution 21,647.30 -5.40%Forestry & Paper 9,704.99 -4.25%Industrial Metals & Mining 1,247.67 -2.68%Mining 15,421.66 -2.09%Personal Goods 23,677.28 -1.65%BC