UK stocks sank to their lowest levels in two weeks today, with escalating tensions in Ukraine prompting a sharp reduction in risk appetite.This saw investors flee towards safe-haven assets, such as gold and silver, today, pushing the share prices of precious metal producers Randgold and Fresnillo higher - although these were the only two stocks in positive territory by mid-afternoon. Randgold also benefitted from Citi's decision to raise its target price from 4,897p to 4,934p. Meanwhile, William Hill retreated from Friday's gains which saw it move higher despite the fact its annual pre-tax profit fell 6% to £257m as the gaming company invested heavily in it its online offering.A target price reduction from Citi - from 100p to 96p - helped push RSA Insurance into the red. Financial stocks were also out of favour, including Aberdeen Asset Management, Schroders, Hargreaves Lansdown and RBS. Airlines IAG and easyJet were also seeing a bit of selling pressure, along with travel firms Carnival and TUI Travel.AstraZeneca was lower after being downgraded to 'underperform' from 'neutral' at Bank of America Merrill Lynch, despite revealing today that the US Food and Drug Administration (FDA) has approved its injectable treatment for type 2 diabetes. FTSE 100 - RisersRandgold Resources Ltd. (RRS) 4,923.00p +3.71%Fresnillo (FRES) 957.50p +0.63%FTSE 100 - FallersWPP (WPP) 1,257.00p -3.90%Aberdeen Asset Management (ADN) 375.40p -3.89%Schroders (SDR) 2,610.00p -3.80%William Hill (WMH) 383.50p -3.55%Rio Tinto (RIO) 3,326.50p -3.09%Standard Life (SL.) 378.10p -3.05%Aviva (AV.) 459.40p -3.00%Carnival (CCL) 2,390.00p -2.96%RSA Insurance Group (RSA) 94.40p -2.93%Babcock International Group (BAB) 1,428.00p -2.92%NR