Investing.com - Investors are eagerly awaiting the Jackson Hole gathering of central bankers this week.ECB President Mario Draghi and Fed Chair Janet Yellen are both to appear on Friday.The big question going in is whether tighter monetary policy might not be warranted.Last week’s Fed minutes noted that keeping policy loose poses risks to financial stability and the economy.Some investors believe Yellen may make the case for a third rate hike this year.Markets are also looking for confirmation that the ECB will soon begin tapering stimulus.Signs of a shift away from monetary easing could see upward pressure on bond yields and a continued rise in overall market volatility from current low levels.