Defensive stocks were in demand in London on Friday as investors sold off 'riskier' assets in search for safety amid heightened geopolitical tensions across the globe.World leaders have demanded answers after the shooting down of a Malaysia Airlines jet over eastern Ukraine, with 298 people on board. While Kiev has claimed that pro-Moscow rebels were behind the attack, Russia's Defence Ministry has pointed the finger at Ukrainian ground forces.Meanwhile, news that the Israeli military has sent ground troops into Gaza to fight with Palestinian militants also dampened sentiment across global financial markets."With this being week-end and geopolitical risk such an unknown quantity, be prepared for some risk aversion on this, sadly, less-than-happy Friday," said Mike van Dulken, Head of Research at Accendo Markets.Stocks in the real estate investment trust (REIT), pharmaceuticals and utilities sectors were among the best performers as lower-beta, non-cyclical stocks benefited from a reduction in risk appetite.REITs such as British Land, Land Securities and Hammerson were putting in decent gains this afternoon, along with utility peers Severn Trent, United Utilities and National Grid.Meanwhile, pharma stocks were being helped higher by yet another bit of M&A in the sector, with Shire agreeing to a £32bn takeover by US group AbbVie. The offer represents a 53% premium to Shire's share price of £34.67 on May 2nd, which was the last day before AbbVie made the first of its five offers for Shire.Top performing sectors so far todayReal Estate Investment Trusts 2,796.82 +0.61%Pharmaceuticals & Biotechnology 13,249.31 +0.49%Gas, Water & Multiutilities 5,980.38 +0.47%Health Care Equipment & Services 5,756.57 +0.04%Bottom performing sectors so far todayAutomobiles & Parts 8,071.00 -2.57%Industrial Transportation 2,843.55 -1.45%Real Estate Investment & Services 2,572.03 -1.16%Insurance (non-life) 1,918.88 -1.11%Financial Services 7,807.19 -1.08%BC