Uncertainty over sovereign debt and the volatility in world markets could mark a period of "2008 redux," and the best option for investors is to remain cautious with long-term assets and hold on to cash, Julian Pendock, a partner at Sendock Capital, told CNBC

"Holding cash is a bit like having a parachute when you jump out of a plane. If you don't have a parachute, you don't hold cash, you're not defensive, there's no parachute and you go into free fall," he said.